Abcd is a parallelogram. find the measure of angle b

Right triangle lmn has vertices l(7, –3), m(7, –8), and n(10, –8). the triangle is translated on the coordinate plane so the coordinates of l’ are (–1, 8). (x, y) → (x + 6, y – 5) (x, y) → (x – 6, y + 5) (x, y) → (x + 8, y – 11) (x, y) → (x – 8, y + 11)