Tính giá trị của biểu thức.

a) Nếu a = 5 thì 388 - 52 ´ a = 388 - 52 ´ 5

                                               = 388 - 260

                                               = 128

b) Nếu b = 45 thì 107 + b : 5 = 107 + 45 : 5

                                               = 107 + 9

                                               = 116

c) Nếu a = 424, b = 4 thì a - b ´ 6 = 424 - 4 ´ 6

                                                       = 424 - 24

                                                       = 400

d) Nếu a = 16, b = 4 thì (20 + a) ´ b = (20 + 16) ´ 4

                                                          = 36 ´ 4

                                                          = 144