How do you solve #-4y - 15= 8y + 9#?

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Answer 1 · 2017-06-22T05:39:59

#y=-2#

When solving one-variable equations, the goal is to isolate that variable.

#-4y-15=8y+9#

The first step is to put all #y# terms on one side of the equation, and all constants on the other side.

Subtract #8y# on both sides.

#-12y-15=9#

Then, add 15 on both sides.

#-12y=24#

Last, you divide -12 on both sides to completely isolate #y#.

#y=-2#

In summary, to isolate variables you just have to perform the inverse of operations until the variable is completely on its own.