Tina bought some gifts for her friends at an average price of $13.20. If Tina 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 gifts would become $14.40. How many gifts did Tina buy for her friends?
| |
Friends |
Friends and parents |
| Number |
1 u |
1 u + 2 |
| Value |
13.20 |
14.40 |
| Total Value |
13.20 u |
14.40 u + 28.80 |
Number of gifts that Tina bought for her friends = 1 u
Amount that Tina spent on the gifts for her friends
= 1 u x 13.20
= 13.20 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 friends
= 1 u + 1 + 1
= 1 u + 2
Total amount that she spent if she bought for her parents and her friends
= 14.40(1 u + 2)
= 14.40 u + 28.80
13.2 u + 54 = 14.40 u + 28.80
14.40 u - 13.2 u = 54 - 28.80
1.2 u = 25.20
1 u = 25.20 ÷ 1.2 = 21
Number of gifts that she bought for her friends
= 1 u
= 21
Answer(s): 21
