In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data
x + 5y = 20 eq.1
2x - 7y = -45 eq.2
x = ?
y = ?
Step 02:
Elimination method
x + 5y = 20 * (-2)
2x - 7y = -45
-2x - 10y = -40
2x - 7y = -45
______________
-17y = - 85
y = -85 / - 17
y = 5
eq.1
x + 5y = 20
x + 5(5) = 20
x + 25 = 20
x = 20 - 25
x = - 5
The answer is:
y = 5
x = -5