subtract the two equation from each other
-3x-7y=-66
-10x-7y=-24
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7x =-42
x=-6
by substituting in equation 1
(-3)(-6)-7y=-66
18-7y=-66
-7y=-84
y=12
so to check we substitute in the first equation
(-3*-6)-(7*12)=-66
18-84=-66
-66=-66
we check the second equations
-10(-6)-7(12)=-24
60-84=-24
-24=-24
