distribute - 12 into (x+5) ----> -12x + - 60
Now you would move - 60 onto the other side of the equal sign: 144 + 60 = -12x (side note: it becomes positive 60 bc you need to cancel out the negative 60 in order to move 60, make sense?)
Next add 144 and 60 together. Once you get your answer divide 12 on each side that way you're left with (answer) = 1x.