Bài 4 : Bài giải
a, ( 187 - 23 ) - ( 20 - 180 ) = 164 + 120 = 284
b, ( - 50 + 19 + 143 ) - ( - 79 + 25 + 48 ) = 112 - ( - 6 ) = 118
c, ( - 37 - 17 ) . ( - 9 ) + 35 . ( - 9 - 11 ) = - 54 . ( - 9 ) + 35 . ( - 20 ) = 486 - 700 = - 214
d, ( - 25 ) ( 75 - 45 ) - 75 ( 45 - 25 ) = - 25 x 30 - 75 x 20 = 25 x 10 ( - 1 x 3 - 3 x 2 ) = 250 x ( - 9 ) = - 2250