Help I don’t know how to find it!

The answer is 130.
Using the triangle sum theorem you get 50 for 1.
Then, angles 1 and 2 must equal 180.
x+50=130
x=130

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.

The surface area would be 576 because you multiply all the numbers then multiply that number by 6