Answer
40 years old
Work Step by Step
Lets denote his daughter's age from seven years ago x.
At that time his age was 11x. Today he is four times older than his daughter 4(x+7), we write x+7 because x is her age from seven years ago and in order to express her age these days we have to add seven.
11x+7=4(x+7)
11x+7=4x+28
7x+7=28
7x=21
x=3
11$\times$3+7=40
