The ratio of Justin's age to John's age is 3 : 1. Last year, their average age was 23. How old will John be in 5 years' time?
| |
Justin |
John |
Total |
| Before |
3 u - 1 |
1 u - 1 |
46 |
| Change |
+ 1 |
+ 1 |
|
| After |
3 u |
1 u |
48 |
Total age of Justin and John this year
= 3 u + 1 u
= 4 u
Total age of Justin and John this year
= 2 x 23 + 1 + 1
= 46 + 2
= 48
4 u = 48
1 u = 48 ÷ 4 = 12
John's age in 5 years' time
= 1 u + 5
= 1 x 12 + 5
= 12 + 5
= 17
Answer(s): 17
