Question

Father told her daughter,"when I was of gour age, you were 4 years old. When you will come to my age, I will be 79 years old. " What are their current ages?

Answer 1

Hope this will help ya
let f = father's present age
let d = daughter's

"When I was your age, you were 4 years old."
(d-4) = the difference in their ages
therefore we can write an equation
f - 2(d-4) = 4
f - 2d + 8 = 4
f - 2d = 4 - 8
f = 2d - 4

" When I will be 79 you will be my present age."
f = 79 - (d-4) 
f = 79 - d + 4
f = 83 - d
Replace f with (2d-4)
2d - 4 = 83 - d
2d + d = 83 + 4
3d = 87
d = 87/3
d = 29 yrs is the daughter's age
then
83 - 29 = 54 yrs is fathers age


Check this: 54 - 29 = 25 years is the difference in their ages
When Dad is daughter's age (29), daughter will be 4 

Answer 2

Hope this answer helps.