The number of durian cakes on display at a cafe was
23 of the number of muffins on display. After 15 durian cakes were bought and the staff added another 30 muffins, the number of muffins was four times the number of durian cakes. The last group of customers bought 4 muffins each, finishing all the muffins on display. How many customers were there in the last group?
| |
Durian cakes |
Muffins |
| Before |
2 u |
3 u |
| Change |
- 15 |
+ 30 |
| After |
2 u - 15 |
3 u + 30 |
Comparing durian cakes
and muffins
in the end |
1 |
4 |
The number of muffins was four times the number of durian cakes in the end.
Number of muffins in the end
= 4(2 u - 15)
= 8 u - 60
8 u - 60 = 3 u + 30 8 u - 3 u = 60 + 305 u = 90
1 u = 90 ÷ 5 = 18Number of muffins in the end= 3 u + 30= 3 x 18 + 30= 84Number of customers in the last group= 84 ÷ 4= 21 Answer(s): 21 
