x+x+18=180 1. Add x+x= 2x. 2. Subtract 18 from each side, which leaves you with 2x=162. 3. Divide each side by 2, that gives you a final answer of x=81
I cant help but if you look up base calculators calc for vertext you justr plug in the numbers and it gives you the answer I can prolly get it for you in a sec