Usha bought some presents for her students at an average price of $13.80. If Usha decided to buy a pen which cost $14 for her father and a bag which cost $40 for her mother, the average price of the presents would become $16.20. How many presents did Usha buy for her students?
| |
Students |
Students and parents |
| Number |
1 u |
1 u + 2 |
| Value |
13.80 |
16.20 |
| Total Value |
13.80 u |
16.20 u + 32.40 |
Number of presents that Usha bought for her students = 1 u
Amount that Usha spent on the presents for her students
= 1 u x 13.80
= 13.80 u
Amount that $(Lizy) spent if she bought for her parents
= 14 + 40
= $54
Total number of items bought if she bought for her parents and her students
= 1 u + 1 + 1
= 1 u + 2
Total amount that she spent if she bought for her parents and her students
= 16.20(1 u + 2)
= 16.20 u + 32.40
13.8 u + 54 = 16.20 u + 32.40
16.20 u - 13.8 u = 54 - 32.40
2.4 u = 21.60
1 u = 21.60 ÷ 2.4 = 9
Number of presents that she bought for her students
= 1 u
= 9
Answer(s): 9
