\(\left[3^4-\left(8^2+14\right):13\right]\cdot x=5^3+10^2\)

\(\Rightarrow\left[81-\left(64+14\right):13\right]\cdot x=125+100\)

\(\Rightarrow\left(81-78:13\right)\cdot x=225\)

\(\Rightarrow\left(81-6\right)\cdot x=225\)

\(\Rightarrow75\cdot x=225\)

\(\Rightarrow x=225:75\)

\(\Rightarrow x=3\)

14 – 5 + 7 = 9 + 7 = 16

22 + 48 – 34 = 70 – 34 = 36

8 +  6 – 9 = 14 – 9 = 5

82 – 37 + 25 = 45 + 25 =  70.

d,[34-(8^2+14):13]:x=25
 [34-(64+14):13]:x=25
 [34-78:13]:x=25
 28:x=25
      x=25.28
      x=700

a)  x = 1 36 + − 3 4

x = 1 + − 27 36 x = − 26 36 x = − 13 18

b)  x = 2 5 + 1 4 + − 1 3

x = 24 + 15 + − 20 60 x = 19 60

=-(23.3.4.7)=-1932

=2.8.14.3=672

=-(34+26+91+99)=-250

=82+(-120)=-(120-82)=-38

=20.(-4)+31.(-20)=20.(-4-31)=20.(-35)=-700

=125+/-25/=125+25=150

=26+34=60

=(-275) +115=-160

=(-34)+34=0

=-18.31-28.(-24)=-555+672=114

\(2575+37-2576-29\)

\(=2612-2576-29\)

\(=36-29=7\)'

\(35+35+36+37-14-15-16-17\)

\(=70+\left(36-16\right)+\left(37-17\right)-14-15\)

\(=70+20+20-14-15\)

\(=90+6-15\)

\(=96-15=81\)

\(13\cdot\left(-12\right)+87.\left(-12\right)\)

\(=\left(-12\right)\cdot\left(13+87\right)\)

\(=\left(-12\right)\cdot100=-1200\)

\(26\cdot17+17\cdot74\)

\(=\left(26+74\right)\cdot17\)

\(=100\cdot17=1700\)

\(25\cdot\left(-18\right)+25\left(-82\right)\)

\(=25\cdot\left[\left(-18\right)+\left(-82\right)\right]\)

\(=25\cdot\left(-100\right)=\left(-2500\right)\)

\(25+37-48-25-37\)

\(=\left(25-25\right)+\left(37-37\right)-48\)

\(=0+0-48\)

\(=0-48=\left(-48\right)\)

\(\left(-16\right)+24+16-34\)

\(=\left[\left(-16\right)+16\right]+\left(24-34\right)\)

\(=0+\left(-10\right)=\left(-10\right)\)

15 - (-15 + 2) = 15 + 13 = 28

(-14) - (17 - 8) = -14 - 9 = -23

15 - (21- 7) = 15 - 14 = 1

34 + (-15) - 17 = 19 - 17 = 2

(-34) + (-12) + 18 = -46 + 18 = -28

27 - 15 - 19 = 12 - 19 = -7

34 - (-15) + 8 = 49 + 8 = 57

-37 + 13 - 25 = -24 - 25 = -49

40 - 17 + (-25) = 23 + (-25) = -2

16 + (-15) - 18 = 1 - 18 = -17

15 - 14 - 13 = 1 - 13 = -12

-27 + 15 - 17 = -12 - 17 = -29

34 - 71 = -37

28 - 125 = -97

13 + (-27) = -14

14 - (-34) = 48

28 - (-16) = 44

-15 - 8 = -23

-27 - 34 = -61

-25 - (-18) = -7

46 - 25 - (-25) = 21 + 25 = 46

-37 - (-24) = -13

46 - (-15) = 61

-26 - 6 + 7 = -32 + 7 = -25

@linhcute

1) 42/35 - [ 33/14 . 21/22 - ( 54/25 : 27/25 - 7/10 )]

= 42/35 - ( 9/4-13/10)

=42/35-19/20

=1/4

2) a) 5/21 . x/34 = 35/102     

x/34=35/102 : 5/21

x/34=49/34

=> x=34

Vậy x=34

b) 15/x . 21/13 = 45/91

15/x=45/91 : 21/13

15/x=15/49

=> x=49

Vậy x=49

lớp 4