Tính giá trị biểu thức: a) 40 : 4 + 67      

a) 40 : 4 + 67                                                b) 27 : 3 – 7

= 10 + 67                                                      = 9 – 7

= 77                                                              = 2

c) 48 – 19 + 36 : 6                                        d) 45 : 5 – 6 + 21

= 48 – 19 + 6                                                = 9 – 6 + 21

= 29 + 6                                                        = 3 + 21

= 35                                                              = 24