Question 309027
Let us consider Khalid's daughter's age as x years
Hence Khalid's present age is 4x

10 years ago daughters age was (x - 10) years
10 years ago Khalid's age was (4x - 10)years

10 years ago the sum of their age was 60.

Hence we can write the linear equation as

(x-10)+(4x -10) = 60
or, x - 10 +4x - 10 = 60
or, 5x - 20 = 60

Let us add 20 to either sides now

or, 5x - 20 + 20 = 60 + 20
or, 5x = 80
or, x = 80/5
or, x = 16

Hence the present age of the daughter is 16 years.