... -1 0(0 ,38 - 3,15) = -10 .(- 2 ,77 ) = 27, 7 b) [ ] { } (- 9, 17) (- 20,83) 0,2. + : [ ] { } (- 3,53)- (2 , 47) 0,5 = [ ] )30 .(2 ,0 − : (0 ,56.6) = - 6 : 3 = -2. 4. Tìm x biết : a) [ ] 7, 1x − = 2,3 b) ... 5 2 − . ( ) 5 3 − = ( ) 5 6 − b) ( ) 75 ,0 3 : 0 ,75 = ( ) 75 ,0 2 c) ( ) 2,0 10 : ( ) 2,0 5 = ( ) 2,0 2 d) ( ) − 7 1 2 4 = ( ) 7 1 − 6 e) 125 50 3 = 5 50 3 3 = ( ) 5 50 3 = 10 3 = 1000 ... tính nhanh : a )(- 2,5.0,38.0,4) - [ ] )8 .(1 5,3.125,0 − b) [ ] 2,0). 17, 9(2 ,0.83,20 −+− : [ ] 5,0).53, 3(5 ,0. 47, 2 −− a) [ ] 38,0).4,0.5, 2( − - [ ] 15.3)).8 .(1 25, 0( − = -10.0,38 - (- 10).3,15 = -1 0(0 ,38...