Bài làm

\(A=\frac{0,24\cdot450+0,8\cdot15\cdot5+3\cdot3\cdot8}{65-60+55-50+45-40+35-30+25-20+5}\)

\(A=\frac{0,24\cdot45\cdot10+0,8\cdot15\cdot5+3\cdot3\cdot8}{\left(65-60\right)+\left(55-50\right)+\left(45-40\right)+\left(35-30\right)+\left(25-20\right)+5}\)

\(A=\frac{2,4\cdot45+0,8\cdot75+72}{5+5+5+5+5+5}\)

\(A=\frac{2,4\cdot45+0,8\cdot\frac{5}{3}\cdot45+1,6\cdot45}{30}\)

\(A=\frac{45\left(2,4+\frac{4}{5}\cdot\frac{5}{3}+1,6\right)}{30}\)

\(A=\frac{45\cdot\left(\frac{20}{15}+\frac{36}{15}+\frac{24}{15}\right)}{30}\)

\(A=\frac{3\cdot\frac{80}{15}}{2}\)

\(A=\frac{\frac{80}{5}}{2}\)

\(A=\frac{80}{5}\cdot\frac{1}{2}\)

\(A=\frac{40}{5}\)

\(A=8\)

a)=(-65-35)+(28+172)

=-100+100

=0

b)=34.[-65+(-55)+20)

=34.(-100)

=-3400

c)=168-437-168-105+437

=(168-168)+(-437+437)-105

=0+0-105

-105

a; (-65) + 28 + (-35) + 172 

= -(65 + 35) + (28 + 172)

= - 100 +  200

= 100 

b; 34.(-65) + (-55).34 + 34.20

= 34.(-65 - 55 + 20)

= 34.(-120 + 20)

= 34.(-100)

= -3400

c; 168 - (437 + 168) + (-105 + 437)

= 168 - 437 - 168 - 105 + 437

= (168 - 168) - (437 - 437) - 105

= 0 - 0 - 105

= -105

a.={75+(-75)}+{15+(-32)}+-55

=0+-17+-55

=0+{(-17)+(-55)

=0+-75

=-75

b. =(35+35)+(65-65)+(24-24)

=70+0+0

=70

không biết đúng hay sai mong mấy bạn thông cảm vì mình cũng không chắc chắn !

     15 + 25 + 35 + 45 + 55 + 65 + 75 + 85

= (15 + 85) + (25 + 75) + (35 + 65) + (45 + 55)

=     100      +    100     +     100     +     100

=                           400

15+25+35+45+55+65+75+85

=(15+85)+(25+75)+(35+65)+(45+55)

=100+100+100+100

=400

15+25+35+45+55+65+75+85

= ( 15+85) +( 25+75)+ ( 35+65)+( 45+55) 

= 100+100+100+100=4 x 100 = 400

 nhanh nhé

35 . 34 + 35 . 38 + 65 . 75 + 65 . 75 + 65 . 45 

= 35 . 65 . ( 34 + 38 + 75 + 75 + 45  )

=   2275 .     267

=      607425

Xin mọi người đừng k sai mình nhé !

35.34+35.38+65.75+65.75+65.45

=35.(34+38).65.(75+75+45)

=35.72.65.195

=3191000

35.( 34+ 38) + 65 . (75 + 75 + 45)

35 . 72 + 65 . 195 

2520 + 12675

15195