1) a + 4 + 3a + 12 = a + 3a + 4 + 12 = a(1 + 3) + 16 = 4a + 16;
2) m * 8 * n * 9 = 72mn;
3) 16x - 7x - 2x = x(16 - 7 - 2) = 7x.
1) a + 4 + 3a + 12 = a + 3a + 4 + 12 = a(1 + 3) + 16 = 4a + 16;
2) m * 8 * n * 9 = 72mn;
3) 16x - 7x - 2x = x(16 - 7 - 2) = 7x.