Question 651324: Harry is two-thirds as old as his sister. Twenty years hence, he will be seven-eights older. How old are they? Answer by shweta(56) (Show Source):
You can put this solution on YOUR website! Let the age of Harry be= H and sister be 'x' years
H= (2/3)*x ....(1)
After 20 years
Harry will be H+ 20 years and his sister= x+ 20
H+20=(7/8)*(x+20) ....(2)
Substitute the value of H in equation 2
(2/3)*x + 20 = (7/8)*x +(7/8)*20
2x/3+ 20 = 7x/8 + 140/8
2x/3 - 7x/8 = 35/2- 20
-5x/24 = -5/2
negative sign get cancelled on both the sides
5x/24 = 5/2
x/24= 1/2
x = 24/2
x=12
harry's sister is 12 years old
Harry's age = (2/3)*12
=8 years
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