The ratio of Luis's age to Wesley's age is 3 : 1. Next year, their average age will be 21. How old will Luis be in 3 years' time?
| |
Luis |
Wesley |
Total |
| Before |
3 u |
1 u |
40 |
| Change |
+ 1 |
+ 1 |
|
| After |
3 u + 1 |
1 u + 1 |
42 |
Total age of Luis and Wesley this year
= 3 u + 1 u
= 4 u
Total age of Luis and Wesley this year
= 2 x 21 - 1 - 1
= 42 - 2
= 40
4 u = 40
1 u = 40 ÷ 4 = 10
Luis's age in 3 years' time
= 3 u + 3
= 3 x 10 + 3
= 30 + 3
= 33
Answer(s): 33
