I need help with the attched problem about definite integrals

We have 
\[\int_{-2}^{2}f(x)dx+\int_2^{5}f(x)dx-\int_{-2}^{-1}f(x)dx=\int_{-2}^{5}f(x)dx-\int_{-2}^{-1}f(x)dx\]
\[=\int_{-2}^{-1}f(x)dx+\int_{-1}^{5}f(x)dx-\int_{-2}^{-1}f(x)dx=\int_{-1}^{5}f(x)dx.\]
So $a=-1$ and $b=5$.

Here we have used the property 
\[\int_{a}^{b}f(x)dx+\int_{b}^{c}f(x)dx=\int_{a}^{c}f(x)dx.\]