Answer:
x = -5; y = 5
Explanation:
x + 5y = 20
-2x + 7y = 45
Multiply both sides of the first equation by 2 to get 2x. Write the second equation below it and add the equations. 2x and -2x add to zero eliminating the x terms.
2x + 10y = 40
-2x + 7y = 45
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17y = 85
y = 85/17
y = 5
Now use substitution in the first original equation to find x.
x + 5y = 20
x + 5(5) = 20
x = -5
Answer: x = -5; y = 5