910 of Andy's savings comprised of 10-cent coins and 50-cent coins. Andy used some 10-cent coins to purchase a doll set. The number of 50-cent coins left was 40% more than the number of 10-cent coins left. Given that Andy had 10 more 50-cent coins than 10-cent coins left in the end, find the amount of money Andy spent on the doll set.
|
10-cent coins |
50-cent coins |
Before |
9x7 = 63 u |
1x7 = 7 u |
Change |
- 58 u |
|
After |
5x1 = 5 u |
7x1 = 7 u |
Fraction of Andy's savings that comprised of 50-cent coins
= 1 -
910=
110Number of 50-cents coins in the end in percentage
= 100% + 40%
= 140%
140% =
140100 =
75Number of 50-cent coins remains unchanged. Make the number of 50-cent coins the same. LCM of 1 and 7 is 7.
Number of more 50-cent coins than 10-cent coins
= 7 u - 5 u
= 2 u
2 u = 10
1 u = 10 ÷ 2 = 5
Number of 10-cent coins spent on the doll set
= 63 u - 5 u
= 58 u
= 58 x 5
= 290
Amount that Andy spent on the doll set
= 290 x 0.1
= $29
Answer(s): $29