Marion bought some presents for her friends at an average price of $13.90. If Marion decided to buy a pen which cost $19 for her father and a bag which cost $42 for her mother, the average price of the presents would become $14.10. How many presents did Marion buy for her friends?
| |
Friends |
Friends and parents |
| Number |
1 u |
1 u + 2 |
| Value |
13.90 |
14.10 |
| Total Value |
13.90 u |
14.10 u + 28.20 |
Number of presents that Marion bought for her friends = 1 u
Amount that Marion spent on the presents for her friends
= 1 u x 13.90
= 13.90 u
Amount that $(Lizy) spent if she bought for her parents
= 19 + 42
= $61
Total number of items bought if she bought for her parents and her friends
= 1 u + 1 + 1
= 1 u + 2
Total amount that she spent if she bought for her parents and her friends
= 14.10(1 u + 2)
= 14.10 u + 28.20
13.9 u + 61 = 14.10 u + 28.20
14.10 u - 13.9 u = 61 - 28.20
0.2 u = 32.80
1 u = 32.80 ÷ 0.2 = 164
Number of presents that she bought for her friends
= 1 u
= 164
Answer(s): 164
