Question 259755
You are right it doesn't look right!
r=7 s=4

7r-4s=33
4r+7s=56
--------
3r 3s=89
your addition needs work.
7+4=11 not 3

but worse your approach is wrong 
It is too early to add or subtract.
you have to get the same coefficient for x or y so that when you add or subtract either the x or the y disappear or are eliminated .

multiply the first by 7 and the second by 4
then we will add them to get rid of y's

7*(7r-4s=33)
4*(4r+7s=56)
49r-28s=7*33
16r+28s=4*56
add
65r=7*33+4*56
65r=455
r=7