Betty bought some presents for her cousins at an average price of $12.50. If Betty decided to buy a pen which cost $16 for her father and a bag which cost $35 for her mother, the average price of the presents would become $17.70. How many presents did Betty buy for her cousins?
| |
Cousins |
Cousins and parents |
| Number |
1 u |
1 u + 2 |
| Value |
12.50 |
17.70 |
| Total Value |
12.50 u |
17.70 u + 35.40 |
Number of presents that Betty bought for her cousins = 1 u
Amount that Betty spent on the presents for her cousins
= 1 u x 12.50
= 12.50 u
Amount that $(Lizy) spent if she bought for her parents
= 16 + 35
= $51
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
= 17.70(1 u + 2)
= 17.70 u + 35.40
12.5 u + 51 = 17.70 u + 35.40
17.70 u - 12.5 u = 51 - 35.40
5.2 u = 15.60
1 u = 15.60 ÷ 5.2 = 3
Number of presents that she bought for her cousins
= 1 u
= 3
Answer(s): 3
