Question

the sum of the present age of a father and his son is 40 years 4 years has father will be three times as old as his son will be find their present age​

Answer 1

Let’s define our variables:

D = dad’s age now

S = son’s age now

Given:

D=4S now

D+4=3(S+4) in 4 years

We can expand the second equation:

D+4=3S+12

D=3S+8

And we can subtract it from D=4S

D=4S-(D=3S+8)

0=S-8

S=8 the son’s age now.

D=4S=4(8)=32 the father’s age now

Check:

32+4=3(8+4)

36=3(12)

36=36 Check

I hope this helps you