1) a • (b – c) + d • (b - c) – 7 • (c - b) = (b - c) • (a + d + 7) 2) x • (x - y) + y • (y - x) - 3 •(x - y) = (x - y) • (x – y - 3) 3) x • (a - 2) + y • (2 - a) + (2 - a) = (a - 2) • (x – y - 1) 4) a • (b - 3) + (3 - b) – b • (3 - b) = (b - 3) • (a – 1 + b)
