Lucy bought some presents for her colleagues at an average price of $13.90. If Lucy decided to buy a pen which cost $13 for her father and a bag which cost $39 for her mother, the average price of the presents would become $16.10. How many presents did Lucy buy for her colleagues?
| |
Colleagues |
Colleagues and parents |
| Number |
1 u |
1 u + 2 |
| Value |
13.90 |
16.10 |
| Total Value |
13.90 u |
16.10 u + 32.20 |
Number of presents that Lucy bought for her colleagues = 1 u
Amount that Lucy spent on the presents for her colleagues
= 1 u x 13.90
= 13.90 u
Amount that $(Lizy) spent if she bought for her parents
= 13 + 39
= $52
Total number of items bought if she bought for her parents and her colleagues
= 1 u + 1 + 1
= 1 u + 2
Total amount that she spent if she bought for her parents and her colleagues
= 16.10(1 u + 2)
= 16.10 u + 32.20
13.9 u + 52 = 16.10 u + 32.20
16.10 u - 13.9 u = 52 - 32.20
2.2 u = 19.80
1 u = 19.80 ÷ 2.2 = 9
Number of presents that she bought for her colleagues
= 1 u
= 9
Answer(s): 9
