Three years ago, Billy's age was 20% of Ivan's age. Eleven years from their current age, Billy's age will be 37.5% of Ivan's age. How many years is Ivan older than Billy?
| |
Billy |
Ivan |
Difference |
| Before |
1x5 =
5 u |
5x5 =
25 u |
4x5 =
20 u |
| Change |
+ 3
+ 11 |
+ 3
+ 11 |
|
| After |
3x4 =
12 u |
8x4 =
32 u |
5x4 =
20 u |
20% =
20100 =
15 37.5% =
3751000 =
38The difference in the ages between Billy and Ivan remains unchanged. Make the difference the same. LCM of 4 and 5 is 20.
Increase in Billy's age
= 12 u - 5 u
= 7 u
7 u = 3 + 11
7 u = 14
1 u = 14 ÷ 7 = 2
Number of years that Ivan is older than Billy
= 25 u - 5 u
= 20 u
= 20 x 2
= 40
Answer(s): 40
