Simplify. Combine like terms
7y - 3y = 4y
-12 + 9 = -3
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4y - 3 = 0
Isolate the y. Note the equal sign. What you do to one side, you do to the other side. Do the opposite of PEMDAS.
4y - 3 (+3) = 0 (+3)
4y = 3
4y/4 = 3/4
y = 3/4
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y = 3/4 is your answer
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hope this helps