My son's age
Algebra
Level
2
Two years ago, my age was four times the age of my son. Eight years ago, my age was 10 times the age of my son.
Find my son's age now.
The answer is 11.
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1 solution
m = my age now
s = age of my son now
Two years ago:
m − 2 = 4 ( s − 2 )
m − 2 = 4 s − 8
m = 4 s − 8 + 2
m = 4 s − 6 ( 1 )
Eight years ago:
m − 8 = 1 0 ( s − 8 )
m − 8 = 1 0 s − 8 0
m = 1 0 s − 8 0 + 8
m = 1 0 s − 7 2 ( 2 )
Substituting ( 2 ) in ( 1 ) , we have
1 0 s − 7 2 = 4 s − 6
1 0 s − 4 s = − 6 + 7 2
6 s = 6 6
s = 1 1 answer