Answer:
x=5
Step-by-step explanation:
6x+12x=90
18x=90
x=90/18
x =5
To solve for x:
1: add like-terms
6x+ 12x = 90
Now it is: 18x =90
2: use division on both sides to solve for the variable
18x= 90
18x/18 = 90/18
x = 5