I assume we are solving ?
first times 3 ---> 9a + 12b = -75
2nd times 4 ---> 8a - 12b = 24
add them
17a = -51
a = -3
back into the first:
3(-3) + 4b = -25
4b = -16
b = -4
a = -3 , b=-4
3a+4b=-25
2a-3b=6
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