Question 45841
Multiply by (-5) instead of (5):
-5(3x-9y=10 
15x-45y=20 
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-15x+45y=-50 
+15x-45y=20 
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0 = -30 (false statement) 
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[Graphing shows that the lines are parallel, not perpendicular]

{{{ graph( 300, 200, -6, 5, -10, 10, (1/3)x-(9/10), (15/45)x-(20/45)) }}}