Answer:
x = 4
Step-by-step explanation:
Step 1: Combine like terms
9x + 6 = 42
Step 2: Isolate x by subtracting 6 on both sides
9x = 36
Step 3: Isolate x by dividing by 9 on both sides
x = 4
3x+6+6x=42
9x+6=42
9x+6-6=42-6
9x= 36
Divide by 9 for 9x and 36
9x/9=36/9
x=4
Check answer by using substitution method
3(4)+6+6(4)=42
12+6+24=42
42=42
Answer is x=4
