very confused could someone help me with this

Question

using the elimination method

5r-3s=16
3r+5s=30

Answer 1

Let's say we want to eliminate 's'
So multiply 5 to the first equation
and multiply 3 to the second equation
we get:
25r - 15s = 80
9r + 15s = 90

use the elimination method by adding those two equation -15s and 15s cancels out
we get:
34r = 170

Then r = 5

Answer 2

2c+3d+7-5c