SOLUTION: Two years ago, the sum of the ages of a boy and his sister is 20 years. Three years from now, their ages will differ by 10 years. Form a pair of linear equations and find their pre

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Question 683583: Two years ago, the sum of the ages of a boy and his sister is 20 years. Three years from now, their ages will differ by 10 years. Form a pair of linear equations and find their present age.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Let the boy's age bex
girls age be y
2 years ago their ages
x-2 boy's age
y-2 girls age
(x-2)+(y-2)=20
x+y-4=20
x+y=16...................(1)
3 years hence
their ages will be
x+3 & y+3
(x+3)-(y+3)=10
x-y=10.................(2)
Add (1) & (2)
2x= 26
x= 13 the boy's age
Girls age = 20-13=7
Their ages could be 13 & 7