a. x+3=18 hoặc x+3=-18

x=15 hặc x=-21

b. x+7=38 hặc x+7=-38

x=31 hặc x=-45

\(2x-13=5-x\)

\(\Rightarrow2x+x=5+13\)

\(\Rightarrow3x=18\)

\(\Rightarrow x=6\)

\(-10⋮n-5\Rightarrow n-5\inƯ\left(-10\right)=\left\{\pm1;\pm2;\pm5;\pm10\right\}\)

\(\Rightarrow n\in\left\{6;4;7;3;10;0;15;-5\right\}\)

Vậy.............................

Đặng Tú Phương còn bài 1 làm sao bạn ?

Bài 1 nhân chia trước cộng trừ sau thôi

= 85 x (-18) - 18 x ( -15) = -1530 + 270 = -1260

2x=36+18
2x= 54
x= 54 : 2
x = 27

42-x=13
x= 42-13
x= 29

27.15+27.85
= 27 . ( 15+85)
= 27. 100
= 2700

\(\text{(-123) +|–13| +(-7)}\)

\(\text{= (-123) + 13 + (-7)}\)

\(\text{= (-110) + (-7)}\)

\(=\text{(-117)}\)

b

\(\frac{3}{4}\)-\(\frac{-5}{9}\)-\(\frac{11}{36}\)=\(\frac{27}{36}\)-\(\frac{-20}{36}\)-\(\frac{11}{36}\)=1

\(\frac{1}{9}\)+\(\frac{-5}{3}\)-\(\frac{-13}{18}\)=\(\frac{2}{18}\)+\(\frac{-30}{18}\)-\(\frac{-13}{18}\)=\(\frac{-15}{18}\)=\(\frac{-5}{6}\)

\(\frac{3}{4}-\frac{-5}{9}-\frac{11}{36}=\frac{27}{36}-\frac{-20}{36}-\frac{11}{36}=\frac{47}{36}-\frac{11}{36}=\frac{36}{36}=1\)

\(\frac{1}{9}+\frac{-5}{3}-\frac{13}{18}=\frac{2}{18}+\frac{-30}{18}-\frac{13}{18}=\frac{-28}{18}+\frac{13}{18}=\frac{-15}{18}=\frac{-5}{6}\)

mấy cái câu đầu thì tớ ko hiểu !(thông cảm)

17/60-5/18-64/90= -127/180

ko chắc là đúng^

uk thank you câu'

1,   15-(2x-3)=6

<=>2x-3=15-6

<=>2x=15-6+3

<=>2x=12

<=>x=12:2

<=>x=6

Vậy x=6

2,   (x-2).3=3\(^2\)

<=>x-2=3\(^2\):3

<=>x-2=9:3

<=>x=9:3-2

<=>x=1

vậy x=1

3,   (x+7)-25=13

<=>x+7=13+25

<=>x=13+25-7

<=>x=31

Vậy x=31

4,   450:(x-190)=50

<=>x-190=450:50

<=>x=450:50+/ 190

<=>x=199

Vậy x=199

5,     3 \(^x\)x 2=18

<=>3\(^x\)=18:2

<=>3\(^x\)=9=3\(^2\)

=>x=2

vậy x=2

\(\frac{2}{3}\)x \(\frac{5}{8}\)x \(\frac{8}{15}\)= \(\frac{2}{3}\)x \(\frac{1}{15}\)= \(\frac{2}{45}\)

\(\frac{22}{5}\)x \(12\)x \(\frac{20}{40}\)= \(\frac{22}{5}\)x \(12\)x \(\frac{1}{2}\)= \(\frac{22}{5}\)x 6 = \(\frac{122}{5}\)

\(\frac{7}{2}\)x \(\frac{26}{7}\)x \(\frac{4}{13}\)= \(\frac{91}{7}\)x \(\frac{4}{13}\)