Question

5yrs ago a man was 7times as old as his son .Five years hence the father will be 3times as old as his son. Find their present age.

Answer 1

let the age be man be x and the age of son be y
according to the first eq.
x-5=7(y-5)
x-5=7y-35
x-7y=-35+5
x-7y=-30 --------eq 1

according to the second eq.
x+5=3(y+5)
x+5=3y+15
x-3y=15-5
x-3y=10 ------- eq 2

eq 1 ------ x-7y= - 35
eq2 -------x-3y= 10
----------------
-10y= -25
y= 5/2

using y = 5/2 in eq 2
x-3×5/2 =10
x-15/2=10
x=10 + 15/2
x=5+7.5
x=12.5

therefore , the present age of man is 12.5 and son is 15/2

hope it's right