a) (370 + 12) : 2 = 382 : 2

                  = 191

370 + 12 : 2 = 370 + 6

                  = 376

b) (231 – 100) x 2 = 131 x 2

                   = 262

231 – 100 x 2 = 231 – 200

                   = 31

c) 14 x 6 : 2 = 84 : 2

                   = 42

14 x (6 : 2) = 14 x 3

                  = 42

d) 900 – 200 – 100 = 700 – 100

                   = 600

900 – (200 – 100) = 900 – 100

                   = 800

x + 100 + 12 = 200 + 12

x + 100 + 12 = 212

x + 100         = 212 - 12

x + 100         = 200

                  x = 200 - 100

                  x = 100

x+100+12=212

x+100=212-12

x+100=200

x=200-100

x=100

Vậy x = 100

x+100+12=200+12

x+100+12=212

x+100=212-12

x+100=200

x=200-100

x=100

k mk nhé,ik mak

x ⋮ 12 và x ⋮ 10 nên x BC(12; 10)

Ta có:

12 = 2².3

10 = 2.5

⇒ BCNN(12; 10) = 2².3.5 = 60

⇒ x ∈ BC(12; 10) = B(60) = {0; 60; 120; 180; 240; ...}

Mà 100 < x < 200

⇒ x ∈ {120; 180}

=1028

=36

k nha

a)=900+100+200-200+28

=1028

b)12x3=36

90+100+300-200+14x2=318

12x3=36

ai k mình mình k lại cho

   900 + 100 + 200 - 200 + 14 x 2

= 900 + 100 + 200 - 200 +     28

=                   2028

12 x 3 = 36

k mk nhé bn iu ^_-

900 + 100 + 200 - 200 + 14 x 2 

= 900 + 100 + 200 - 200 + 28

= 900 + 100 +    0          + 28

=   1000  + 28

=   1028

12 x 3 = 36

\(900+100+200-200+14x2\)

\(=900+100+200-200+28\)

\(=1000+200-200+28\)

\(=1200-200+28\)

\(=1000+28\)

\(=1028\)

K nha mình sẽ k bạn hứa luôn!

1000

100

-200

60 nha!

1000

100

100

60

200 + 800 - 100 + 100 = 1000 

100 - 100 + 100 = ?100

300 + 300 - 900 + 100 = -200

12 + 12 + 12 + 12 + 12 = 70

\(12=2^2.3\\ 21=3.7\\ \Rightarrow BCNN\left(12,21\right)=2^2.3.7=84\\ \Rightarrow x\in BC\left(12,21\right)=B\left(84\right)=\left\{0;84;168;252;...\right\}\\ \text{Mà }100< x< 200\Rightarrow x=168\)

\(x\in BC\left(12;21\right)\)

mà 100<x<200

nên x=168

x = 168

\(200:25-\left(12-x\right)=4\\ 8-\left(12-x\right)=4\\ 12-x=8-4\\ 12-x=4\\ x=12-4\\ x=8\\ ---\\ \left(x-10\right).5=100-20.4\\ \left(x-10\right).5=100-80=20\\ x-10=\dfrac{20}{5}=4\\ x=4+10=14\)

a)\(200:25-\left(12-x\right)=4\)

\(\Rightarrow8-\left(12-x\right)=4\)

\(\Rightarrow12-x=8-4\)

\(\Rightarrow12-x=4\)

\(\Rightarrow x=12-4\)

\(\Rightarrow x=8\)

b) \(\left(x-10\right)\cdot5=100-20\cdot4\)

\(\Rightarrow\left(x-10\right)\cdot5=100-80\)

\(\Rightarrow\left(x-10\right)\cdot5=20\)

\(\Rightarrow x-10=4\)

\(\Rightarrow x=10+4\)

\(\Rightarrow x=14\)

A

A

A