What is the value of y, show your work.

The answer is 60° because the total measure of a triangle is 180° so since all sides are equal (you can tell because of the tally mark) just divide by 3 and you will get 60°

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.