a, -326-(115-326)=-326-(-326)-115=(-326+326)-115=-115

b,-13-18-(-42)-15=-13-18+42-15=-4

c,(-558+558)+(-50+50)=0+0=0

d,35-12+16=39

e,18.17-3.6.7=18.17-18.7=18.(17-7)=18.10=180

f,21.7²-11.7²+90.7²+49.125.10

=21.7²-11.7²+90.7²+7².1250

=7².(21-11+90+1250)

=7².1350=49.1350

=66150

\(27.332+93.43+57.61+69.57\\ =27.332+93.43+57.\left(61+69\right)\\ =27.332+93.43+57.130\\ =8964+3999+7410=20373\\ 34.75+75.66-65.100\\ =\left(34+66\right).75-65.100\\ =100.75-65.100\\ =100.\left(75-65\right)\\ =100.10=1000\\ \left(456.11+912\right).37:13:74\\ =5928:13:\left(74:37\right)\\ =456:2=228\\ 6^2:4.3+2.5^2\\ =36:4.3+2.25\\ =9.3+50=27+50=77\\ 5.4^2-18:3^2\\ =5.16-18:9\\ =80-2=78\\\left[\left(315+372\right).3+\left(372+315\right).7\right]:\left(26.13+74.14\right)\\ =687.\left(3+7\right):\left(338+1036\right)\\ 687.10:1374\\ =6870:1374=5\\ 12:\left\{390:\left[500-\left(125+35.7\right)\right]\right\}\\ =12:\left[390:\left(500-370\right)\right]\\ =12:\left(390:130\right)=12:3=4\\ 192000-\left(1500.2+1800.3+1800.2:3\right)\\ =192000-\left(3000+5400+1200\right)\\ =192000-9600=182400\)

a)\(12-\left[25+\left(6+3\right)^2\right]\)

\(=12-\left[25+9^2\right]\)

\(=12-\left[25+81\right]\)

\(=12-106\)

\(=\left(-94\right)\)

b) \(315-\left(8^6\div8^4-12.3+7+7^3\right)\)

\(=316-\left(8^2-36+7+343\right)\)

\(=316-\left(64-43+343\right)\)

\(=316-\left(21+343\right)\)

\(=316-364\)

\(=\left(-48\right)\)

c) \(-81-108\)

 \(=-\left(81+108\right)\)

\(=\left(-189\right)\)

d) \(-13-91\)

\(=-\left(13+91\right)\)

\(=\left(-104\right)\)

e)\(-85-\left(-17\right)\)

\(=-85+17\)

\(=-\left(85-17\right)\)

\(=\left(-68\right)\)

g) \(63.\left(-8\right)+\left(-63\right).92\)

\(=63.\left(-8\right)+63.\left(-92\right)\)

\(=63.\left[\left(-8\right)+\left(-92\right)\right]\)

\(=63.\left(-100\right)\)

\(=\left(-6300\right)\)

a) -132 + (176+132)

= -132+176+132

= -132+132+176

=0+176

= 176

b) 25. (-5).4.(-8)

= (25.4).[-5.(-8)]

= 100 . 40

= 4000

c) -37.52+37. (-48)

= -37.52+(-37).48

= -37.(52+48)

= -37.100

= -3700

d) 54 - 8.(6-23)

= 54 - 8. (-17)

= 54 - (-136)

= 54 + 136

= 190

e) -85 . 13 + 85 . 113

= 85 . (-13) + 85 . 113

= 85. (-13 + 113)

= 85.100

= 8500

f)2008-(107+2008)-75

= 2008 - 107 - 2008 - 75

= 2008 - 2008 - 107 - 75

= -107 - 75

= -182

1. Q=165+247+528+125+315

= 100+60+5+200+40+7+500+20+8+100+20+5+300+10+5

= ( 100+200+500+100+300) + ( 60+40+20+20+10 ) +( 5+7+8+5+5 )

= 1200+150+30

=1280

R=1234+5678+8+80

=1000+200+30+4+5000+600+70+8+8+80

= ( 1000+5000) + ( 200+600 ) + (30+70+80) + ( 4+8+8)

=6000+800+180+20

=7000

còn câu 2 mk lười lắm , bạn nhờ ngừi khác nha ^^ nhớ t i c k nha

Bài 1

Tính : Q=165+247+528+125+315 

=(165+125)+(247+315+528)

=290+1090

= 1380

R=1234+5678+8+80

=(1234+6)+(5678+2)+80

= 1240+5680+80

= (1240+60)+(5680+20)

=1300+5700=7000

Bài 2:

A= 243-97=(243+7)-(97-7)=250-90=160

B= 400-42-58=400-(42+58)=400-100=300

C=600-67-33=600-(67+33)=600-100=500

D=200-24-46=200-(24+46)=200-70=130

E=400-5-6-7-8=400-(5+6+7+8)=400-26=374

F= 764-115-268-43-32-20-85-37

=764-(115+85)-(268+32)-(43+37)-20

=764-200-300-80-20

=164

G=350-7-18-52-48-72

=350-(18+72)-(52+48)-7

=350-90-100-7

=160-7

=153

a, \(\dfrac{7}{15}\)+\(\dfrac{18}{54}\)
=  \(\dfrac{7}{15}\)+ \(\dfrac{1}{3}\)
=  \(\dfrac{7}{15}\)+\(\dfrac{5}{15}\)
=    \(\dfrac{12}{15}\) = \(\dfrac{4}{5}\) =0,8
b, \(\dfrac{12}{25}\)+\(\dfrac{23}{75}\)-\(\dfrac{1}{4}\)
=     \(\dfrac{59}{75}\)   -\(\dfrac{1}{4}\)
=         \(\dfrac{161}{300}\)
   

a, 7/15 + 18/54 = 4/5