Last year, Japheth was 4 times as old as his son, Justin. This year, their total age is 102 years old. How old will Justin be when Japheth is 3 times as old as him?
| |
Japheth |
Justin |
Difference |
Total |
| Before |
4x2 =
8 u |
1x2 =
2 u |
3x2 =
6 u |
|
| Change 1 |
+ 1 |
+ 1 |
|
|
| After 1 |
8 u + 1 |
2 u + 1 |
|
102 |
| Change |
+ ? |
+ ? |
|
|
After 2 |
3x3 =
9 u |
1x3 =
3 u |
2x3 =
6 u |
|
The difference in Ben's age and his son's age always remains unchanged. Make the difference in age the same. LCM of 3 and 2 is 6.
Total age of Japheth and his son this year
= 8 u + 1 + 2 u + 1
= 10 u + 2
10 u + 2 = 102
10 u = 102 - 2
10 u = 100
1 u = 100 ÷ 10 = 10
Japheth's age when Japheth is 3 times as old as him
= 3 u
= 3 x 10
= 30
Answer(s): 30
