Question

The following blank indicates a missing operation in the equation.

Answer 1

The answer would be 5/2q+9r+6r-20s

Explanation
We have the equation
5(1/2q+3r-4s)
which would equal
5/2q+15r-20s

so with the information
We can subtract 6r from 15r to get 9r
15r-6r=9r
+9r would be the missing piece

So we substitute it in to make the equation true.
5/2q(+9r)+6r-20s
Hope this helps or was correct