Answer:
n=30
Explanation:
n+30+2n-10+70=180
We move all terms to the left:
n+30+2n-10+70-(180)=0
We add all the numbers together, and all the variables
3n-90=0
We move all terms containing n to the left, all other terms to the right
3n=90
n=90/3
n=30