Question 981874
let fathers age now be x
daughters age now be y

10 years hence
(x+10)= 2(y+10)
x+10 = 2y+20
x-2y=10

10 years ago
(x-10)= 6(y-10)
x-10 = 6y-60
x-6y=-50

x-2y=10
x-6y=-50

subtract the equations

4y=60
y=15 daughter's age now

substitute y in x-2y=10

so x=40 present father's age