What is the value of y in the solution to the system of equations? x + y = 12x – 3y = –30

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

2y= 3 2 x−2 y = − 1 3 x + 1 y=− 3 1 x+1

Use the formulas a = x 2 – y 2, b = 2xy, c = x 2 + y 2 to answer this question. one leg of a right triangle has length 11 and all sides are whole numbers. find the lengths of the other two sides. the other leg = a0 and the hypotenuse = a1