What numbers should be added to $\frac{-5}{8}$ so as to get $\frac{-3}{2}$?

Let, the required number is $=x$

Then,

 $x+\left(\frac{-5}{8}\right)=\frac{-3}{2}$

 $x-\frac{5}{8}=\frac{-3}{2}$

 $x=-\frac{3}{2}+\frac{5}{8}=\frac{-12+5}{8}$

 $x=\frac{-7}{8}$

Hence, this is the answer.