Question

Simultaneous linear equations

Six tearyhence a man's age will be three times his son's age , and 3 years ago he was 9 times as old as his son. Find their present age.

Answer 1

let their present ages be X and Y.

after six yrs:
father's age=X +6
son's age=Y+6

X+6=3(Y+6)

X+6=3Y+18

X-3Y=18-6

X-3Y=12------1

before three yrs;
father's age=X-3

son's age=Y-3

X-3=9(Y-3)

X-3=9Y-27

X-9Y= -27+3

X-9Y= -24--------2

ELIMINATION METHOD;

X-3Y=12------(1)

X-9Y=-24------(2)

On solving we get

6Y= 36

Y=6-------(3)

Substitute (3)IN(1)

X-3(6)=12

X-18=12

X=12+18

X=30

therfore father's age =30 yrs and son's age=6 yrs