Cuál es el valor absoluto de/ 9-15 /

Hi there! The anser is 4 

First we need to find the value between the stripes. Hence, we need to subtract 15 from 9. Then we get 9 - 15 = - 4. Finally we have to realise that the absolute value stripes make the value insides those stripes positive. So, we get the following:
I 9 - 15 I = I - 4 I = 4