solve by addition/subtraction method
-10x-6y=0
-1(-4x-6y=54)
which changes to:
-10x-6y=0
4x+6y=-54
then we can solve for x:
-6x=-54
bring the -6 over by division to isolate "x"
x=9
chose one of the equations and replace the "x" with 9 to find the value of "y"
-10(9)-6y=0
-90-6y=0
-6y=90
y=-15
so the answer is (9,-15)
