<PRE><B>Question 1155559</B>
5 x-3y = 18
-3 x-3y = -12
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Substitution is not a good choice here, tho you might be instructed to use it.
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If you mean:
5x -3y = 18
-3x-3y = -12
---------------------- Subtract
8x = 30
x = 15/4
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Sub for x in either equation and find y.
-3 x-3y = -12
x + y = 4
y = 4 - 15/4
y = 1/4</PRE>