1) 17.(-84) + 17.(-16)  =  17.(-84-16) = 17.(-100) = -1700

2) 15.(58) - 15.(48) = 15.(58 - 48) = 15.(10) = 150

3) -37.(86) + 37.(76) = 37.(-86 + 76) = 37.(-10) = -370

4) 1975.(-115) + 1975.(15) = 1975.(-115+15) = 1975.(-100) = -197500

5) 79.(89) - 79.(-11) = 79.(89+11) = 79.(100) = 7900

6) 48.(195) - 48.(95) = 48.(195 - 95) = 48.(100) = 4800

7) 157.(17) - 157.(7) = 157.(17-7) = 157.(10) = 1570

8) 15.(-176) + 15.(76) = 15.(-176+76) = 15.(-100) = -1500

9) 47.(-147) - 47.(-47) = 47.(-147 + 47) = 47.(-100) = -4700

10) 153.(177) - 153.(77) = 153.(177-77) = 153.(100) = 15300

11) 15.(4-7) - 15.(5-3) = 15.(-3) - 15.(2) = 15.(-3-2) = 15.(-5) = -75

12) 73.(8-59) - 59.(8-73) = 73.(8) - 73.(59) - 59.(8) + 59.(73)

= 73.(8-59+59) - 59.(8) = 73.(8) - 59.(8) = 8.(73-59) = 8.(14) = 112

13) 159.(18-59) - 59.(18-159) = 159.(18) - 159.(59) - 59.(18) + 59.(159)

= 159.(18-59+59)  - 59.(18) = 159.(18) - 59.(18) = 18.(159-59) = 18.(100) = 1800

14) -145.(13-57) + 57.(10-145) = -145.(13) + 145.(57) + 57.(10) - 145.(57) 

= 145.(-13+57-57) + 57.(10) = 145.(-13) + 57.(10) = -1315

15) 17.(15-16) + 16.(17-20) = 17.(-1) + 16.(-3) = -17 - 48 = -65

16) -38.(25-4) + 25.(-4+38) = -38.(25) + 38.(4) - 25.(4) + 25.(38) 

= 38.(-25+4+25) - 25.(4) = 38.(4) - 25.(4) = 4.(38-25) = 4.(13) = 52

17) 23.(145-17) - 145.(23-6) = 23.(145) - 23.(17) - 145.(23) + 145.(6) 

= 23.(145-17-145) + 145.(6) = 23.(-17) + 145.(6) = 479

18) 24.(15-4) + 4.(24-15) = 24.(15) - 24.(4) + 4.(24) - 4.(15) 

= 24.(15-4+4) - 4.(15) = 24.(15) - 4.(15) = 15.(24-4) = 15.(20) = 300

19) 199.(15-17) - 199.(-17+5) = 199.(-2) - 199.(-12) = 199.(-2+12)

= 199.(10) = 1990

20) -39.(5-99) + 99.(10-39) = -39.(5) + 39.(99) + 99.(10) - 99.(39)

= 99.(39+10-39) - 39.(5) = 99.(10) - 39.(5) = 990 - 195 = 795

Chúc bạn học tốt !!!