Dana bought some presents for her cousins at an average price of $12.20. If Dana decided to buy a pen which cost $12 for her father and a bag which cost $43 for her mother, the average price of the presents would become $15.60. How many presents did Dana buy for her cousins?
| |
Cousins |
Cousins and parents |
| Number |
1 u |
1 u + 2 |
| Value |
12.20 |
15.60 |
| Total Value |
12.20 u |
15.60 u + 31.20 |
Number of presents that Dana bought for her cousins = 1 u
Amount that Dana spent on the presents for her cousins
= 1 u x 12.20
= 12.20 u
Amount that $(Lizy) spent if she bought for her parents
= 12 + 43
= $55
Total number of items bought if she bought for her parents and her cousins
= 1 u + 1 + 1
= 1 u + 2
Total amount that she spent if she bought for her parents and her cousins
= 15.60(1 u + 2)
= 15.60 u + 31.20
12.2 u + 55 = 15.60 u + 31.20
15.60 u - 12.2 u = 55 - 31.20
3.4 u = 23.80
1 u = 23.80 ÷ 3.4 = 7
Number of presents that she bought for her cousins
= 1 u
= 7
Answer(s): 7
