а) 4 300 - 43 * 99 = 43 * 100 - 43 * 99 = 43 * (100 - 99) = 43 * 1 = 43
б) 999 * 156 + 156 = 999 * 156 + 156 * 1 = 156 * (999 + 1) = 156 * 1 000 = 156 000
