Father’s age is 4 times that of his son. 5 years back, it was 7 times. His age now is

Ok.  You can use whatever symbols you like for both son's age and father's age.  Let me use x for son's age and y for father's age then.

father (y) is now 4 times as old as son (x) is now.   y = 4x   ...(1)

5 years ago father was y-5 years old, and son was x-5 years old.  At that time father was 7 times as old as his son.

 y - 5 = 7*(x - 5)    ...(2)

Replace the y in (2) by using (1)

4x - 5 = 7*(x - 5)

4x - 5 = 7x - 35

4x - 5 + 35 = 7x 

4x +30 = 7x

4x + 30 - 4x = 7x - 4x

30 = 3x

x = 10  ...(3)

Put (3) into (1)

y = 4*10

y = 40

Is this any clearer?

Let f = father's age and s = son's age

f = 4*s                                 father is 4 times older than son

f - 5 = 7*(s - 5)                   5 years ago father was f -5 and son was s-5  and father was 7 times older

Replace f in 2nd equation above with 4s from first equation,

4*s - 5 = 7*s - 7*5  so that:

30 = 3*s

s = 10

f = 4*10 = 40

Alan this question is still confusing me . Can you please put x in place of sons age and then try and solve this maybe that way I can understand this much easily!

wow Alan that was so easy!Thank u so much!i would give u a point for a clearer answer!Thank you!