The ratio of Mark's age to John's age is 10 : 9. Last year, their average age was 18. How old will John be in 6 years' time?
| |
Mark |
John |
Total |
| Before |
10 u - 1 |
9 u - 1 |
36 |
| Change |
+ 1 |
+ 1 |
|
| After |
10 u |
9 u |
38 |
Total age of Mark and John this year
= 10 u + 9 u
= 19 u
Total age of Mark and John this year
= 2 x 18 + 1 + 1
= 36 + 2
= 38
19 u = 38
1 u = 38 ÷ 19 = 2
John's age in 6 years' time
= 9 u + 6
= 9 x 2 + 6
= 18 + 6
= 24
Answer(s): 24
