Question 375628
3a-3b=-15
-3a-3b=-3
..
add up the equations
3a-3a-3b-3b=-15-3
-6b=-18
/-6
b=-18/-6
b=3
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plug value of b in first equation
3a-3b=-15
3a-3*3=-15
3a-9=-15
+9
3a=-15+9
3a=-6
/3
a=-2
(-2,3)
..
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