a)7 * 49 + 7 * 31 - 7 * 50 = 7(49 + 31 - 50) = 7 * 30 = 210
b) 32 * 25 +32 * 11 - 36 * 30 = 32(25 + 11) - 36 * 30 = 32 * 36 - 36 * 30 =
36 * (32 - 30) = 36 * 2 = 72
c) 99 * 11 + 13 * 11 - 112 = 11* (99 + 13) - 112 = 11 * 112 - 112 =
112 * (11 - 1) = 112 * 10 = 1120
d) 177 * 36 - 177 * 31 - 77 * 5 = 177 * (36 - 31) - 77 * 5 = 177 * 5 - 77 * 5 =
5 * (177 - 77) = 5 * 100 = 500