The ratio of Cody's age to Charlie's age is 10 : 9. Next year, their average age will be 20. How old will Cody be in 3 years' time?
| |
Cody |
Charlie |
Total |
| Before |
10 u |
9 u |
38 |
| Change |
+ 1 |
+ 1 |
|
| After |
10 u + 1 |
9 u + 1 |
40 |
Total age of Cody and Charlie this year
= 10 u + 9 u
= 19 u
Total age of Cody and Charlie this year
= 2 x 20 - 1 - 1
= 40 - 2
= 38
19 u = 38
1 u = 38 ÷ 19 = 2
Cody's age in 3 years' time
= 10 u + 3
= 10 x 2 + 3
= 20 + 3
= 23
Answer(s): 23
