Answer:
-40
Explanation:
This is a "two-step" linear equation.
First step: eliminate the constant +5 on the left by adding its opposite.
y/-4 +5 -5 = 15 -5
y/-4 = 10
Second step: eliminate the 'divided by' by multiplying by that amount:
-4(y/-4) = -4(10)
y = -40
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Of course, whatever we do to one side of the equation (add, multiply), we must also do to the other side of the equation. That is how the equal sign stays valid.