Verified answer

hey

9y - 63 = 9 * y - 9 * 7 = 9 (y - 7)

12y - 42 = 6 * 2y - 6 * 7 = 6 (2y - 7)

5y + 5 = 5 * y + 5 * 1 = 5 (y + 1)

7y - 7z = 7 * y - 7 * z = 7 (y - z)

xy + yz = y * x + y * z = y (x + z)

x² + 3x = x * x + x * 3 = x (x + 3)

Salut

Bonne continuation :-)