Flynn's current age is 9 times as old as David's age years ago. Today, David's age is Flynn's age the same number of years ago. How old is David's age now if the total of their current age is 56?
| |
Flynn |
David |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
9 u |
1 p |
9 u - 1 p |
56 |
Total age of Flynn and David today = 9 u + 1 p
9 u + 1 p = 56 --- (1)
The difference in Flynn's age and David's age remains the same.
9 u - 1 p = 1 p - 1 u
9 u + 1 u = 1 p + 1 p
10 u = 2 p
5 u = 1 p
Substitute 1 p = 5 u into (1).
9 u + 1 p = 56
9 u + 5 u = 56
14 u = 56
1 u = 56 ÷ 14 = 4
Flynn's age now
= 56 - 9 u
= 56 - 9 x 4
= 56 - 36
= 20
Answer(s): 20
