Question

a man is 4 times as old as her daughter. after 16 year he will be twice as old as her daughter find the daughter age

Answer 1

x = daughter's age now
4x = man's age now 

x + 16 = daughter's age in 16 years
4x + 16 = man's age in 16 years 

2(x + 16) = 4x + 16 {in 16 years he will be twice as old as his daughter}
2x + 32 = 4x + 16 {used distributive property}
2x = 16 {subtracted 2x and 16 from each side}
x = 8 {divided each side by 2} 

daughter is 8