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;
```