Answer:
y = 10 , x= -3
Note: I have never hears this called "combination method"
if you research this on-line it is typically called the "elimination" or the "addition" method.
Explanation:
5x + y = 5
10x + 3y = 20
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multiply top equation by -2
-10x + -2y = -10
10x + 3y = 20
y = 10
x= -3