Tính

a) 914 : 912                                                       b)32 .86 – 81. 32

c) 230 + 78  -230 -58                                     d) 2 . 42 + 62  : 3

Baøi 2: Tìm x, bieát:

a) x + 15 =  5                                                   b) 125 – (x + 2) = 121