The age of father is 4nyears. If the age of his daughter is (2n-9) years. find their total age.

4n + (2n-9)

4n+2n-9

6n-9 = the total age

6n=9

divide by 6 both sides.

n=9/6

n=1.5 years.

substitute the value of n in the age of the father and the daughter.

Age of father=4*1.5

6years.

Age of Daughter = (2*1.5) - 9

3-9

=-6 years

Total age

6-6=0