Age of Ben is 40 and age of his daughter ** is **10.
Solution:
Consider Ben’s age be x & his daughters age be y.
So, Ben is four times as old as his daughter.
x = 4y ....(1);
In 20 years’ time Ben shall be twice as old as her.
x+20 = 2(y+20) ....(2);
now, adding x=4y equ(1) in equ(2),
4y+20 = 2y+40;
4y-2y = 40-20;
2y = 20;
y = 10;
So, y=10 adding in equ(1)
x = 4(10);
x = 40;