Answer:
X = 5
Explanation:
3x + 12 + 9x = 72
okay hopefully i can explain so when your doing this combine like terms so
3x + 9x = 12x
12x + 12 = 72
then you would subtract both sides by 12
+12 = subtract x+12=2
- 12 = add x-12=2
there just flipped so in this case i would subtract 12
12x + ( 12-12) = ( 72-12 )
so 12-12 = 0 and 72-12 is equal to 60
12x = 60
the divide on both sides l but leave the x alone so its just 60 divided by 12 wich is 5
so X = 5
hope this helps with ur homework a little btw go back and redo ur other awnsers with this new concept hope it helps