The number of cheese cakes on display at a cafe was
56 of the number of biscuits on display. After 20 cheese cakes were bought and the staff added another 39 biscuits, the number of biscuits was thrice the number of cheese cakes. The last group of customers bought 7 biscuits each, finishing all the biscuits on display. How many customers were there in the last group?
| |
Cheese cakes |
Biscuits |
| Before |
5 u |
6 u |
| Change |
- 20 |
+ 39 |
| After |
5 u - 20 |
6 u + 39 |
Comparing cheese cakes
and biscuits
in the end |
1 |
3 |
The number of biscuits was thrice the number of cheese cakes in the end.
Number of biscuits in the end
= 3(5 u - 20)
= 15 u - 60
15 u - 60 = 6 u + 39 15 u - 6 u = 60 + 399 u = 99
1 u = 99 ÷ 9 = 11Number of biscuits in the end= 6 u + 39= 6 x 11 + 39= 105Number of customers in the last group= 105 ÷ 7= 15 Answer(s): 15 
