ok. 5x+6=2x+15
the first think we have to do is combine like terms. we need to put all the x on one side and all the regular numbers on the other side.
5x+6=2x+15
-6 -6
5x=2x+9
-2x -2x
3x=9
the next thing we have to do is isolate the x from the regualar numbers. since divition is the opposite of multiplication we divide to undo the division
3x=9
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3 3
x=3