Understand the idea.
Money collected is not all spare money
A class enterprise might make cards for a school stall. Before starting, decide how many to make, what materials cost and what price to charge. The money collected from customers is the sales total.
Sales money is not all spare money. Materials have already used some of it. Subtract all stated costs from the sales total to find what remains for saving, sharing or another stall.
| Item | Calculation | Amount |
|---|---|---|
| Make 10 cards at 20 cents each | 10 × 20 cents | 2 dollars cost |
| Sell all 10 cards at 50 cents each | 10 × 50 cents | 5 dollars collected |
| Money left after materials | 5 dollars − 2 dollars | 3 dollars |
Consider people as well as totals
A good plan considers people as well as money. Discuss how jobs will be shared and how any money left will help the class or its chosen community purpose. Families should be free to choose whether to buy.
Say what a calculation assumes. The card plan assumes every card sells and there are no other costs. If some cards remain unsold, their materials still cost money, but they have not brought in sales money.
See the method in action.
Find money left after costs
A class makes 10 cards. Each costs 20 cents to make and sells for 50 cents. All sell. How much remains after materials?
Worked solution
- 1
Find the materials cost.
Materials are needed for all ten cards.
- 2
Find the sales total.
The question says all ten cards sell at 50 cents each.
- 3
Take away the materials cost.
Only the sales money beyond the stated cost remains.
- 4
Name the remainder in dollars.
Each group of 100 cents makes one dollar.
3 dollars remain after materials.
Share and save
A stall collects 4 dollars in sales. Its materials cost 2 dollars. The class gives 1 dollar to its chosen community project. How much remains for the next stall?
Worked solution
- 1
Cover the materials first.
The sales total must pay the stated materials cost.
- 2
Take away the community gift.
The gift uses one dollar of the money remaining after costs.
- 3
Check where all four dollars went.
Materials, gift and money saved together account for the whole sales total.
1 dollar remains for the next stall.
Try it yourself.
Check your understanding
A stall collects 6 dollars. Materials cost 4 dollars. How much is left after costs?
Show answer & reasoning
2 dollars.
Subtract the materials cost from the sales total: dollars. The stall collected six dollars, but only two dollars remain after costs.
Keep practising
6 worksheet questions
Read the questions online
- Six cards sell for 50 cents each. How much money is collected?
- A class makes 10 cards costing 20 cents each. It sells only 6 for 50 cents each. How much remains after all materials costs?
- After costs, a stall has 3 dollars. The class gives 1 dollar to a chosen project. How much is left?
- Badges sell for 50 cents each. How many must sell to collect 4 dollars? This asks for sales money before costs.
- The materials budget is 3 dollars. Card costs are 2 dollars 50 cents and labels cost 70 cents. A cheaper label set costs 40 cents. Which label set fits the budget?
- A class has 2 dollars left after costs. Suggest a plan that considers other people and the next stall. Show that the plan uses no more than 2 dollars.
Read the worked solutions
- Six cards sell for 50 cents each. How much money is collected?
cents, or 3 dollars.
3 dollars. - A class makes 10 cards costing 20 cents each. It sells only 6 for 50 cents each. How much remains after all materials costs?
All materials cost cents. Sales collect cents. cents remain.
1 dollar. - After costs, a stall has 3 dollars. The class gives 1 dollar to a chosen project. How much is left?
dollars.
2 dollars. - Badges sell for 50 cents each. How many must sell to collect 4 dollars? This asks for sales money before costs.
4 dollars are 400 cents. Eight groups of 50 cents make 400 cents.
8 badges. - The materials budget is 3 dollars. Card costs are 2 dollars 50 cents and labels cost 70 cents. A cheaper label set costs 40 cents. Which label set fits the budget?
cents is too much. cents fits within 300 cents; .
The 40-cent labels fit, with 10 cents left. - A class has 2 dollars left after costs. Suggest a plan that considers other people and the next stall. Show that the plan uses no more than 2 dollars.
dollars. Another explained plan within the budget is acceptable.
For example, use 1 dollar for shared supplies and save 1 dollar for the next stall.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics
Dollars/cents; equivalent amounts; modelling purchases; needs/wants; class enterprise and others' wellbeing.
Official curriculum source ↗