Question

(x+y) (a+b)-(y+z) (a+b)

Answer 1

Answer:

$(x + y)(a + b) - (y + z)(a + b) \\xa + xb + ya + yb - (ya + yb + za + zb \\ \\ = xa + xb + ya + yb - ya - yb - za - zb \\ = xa + xb - za - zb \\ = a(x - z) + b(x - z) \\ = (x - z)(a + b)$