First, write the equation in canonical form:

r + 2s = -1,    (1)
r + 5s = -28.   (2)

Distract equation (1) from equation (2) (both sides). 
In this way you eliminate the unknown r and obtain a singular equation for the unknown s:You will get

5s - 2s = -28 - (-1) = -27.

Hence, s =  = -9.

Then from (1) r = -1 - 2s = -1 -2*(-9) = -1 +18 = 17.

Answer. The solution is r = 17, s = -9.

Please check yourself the solution. Simply substitute the found values into the original equations (1) and (2).