12x=4(x+5) (multiplying 4 by each argument in the parenhesis) 12x=4x+20 /-4x both sides 8x=20 /:8 divide both sides by 8 [tex]x= \frac{20}{8}= 2 \frac{4}{8}=2.5 [/tex]
15x-3(3x+4)=6 (-3 times each argument in the parenthesis) 15x-9x-12=6 6x-12=6 /+12 both sides 6x=18 /:6 divide both sides by 6 x=3
3x-5x+10=36 -2x+10=36 /-10 both sides -2x=26 /:(-2) divide both sides by -2 x=-13