![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
1.
=3/5x(3/7+4/7)+2/5x(13/9-4/9)
=3/5x1+2/5x1
=3/5+2/5
=1
2.Xx(3/4+4/5)=7/10
Xx31/20=7/10
X =7/10:31/20
X =14/31
\(\frac{3}{5}\cdot\frac{3}{7}+\frac{3}{5}\cdot\frac{4}{7}+\frac{2}{5}\cdot\frac{13}{9}-\frac{2}{5}\cdot\frac{4}{9}\)
\(=\frac{3}{5}\cdot\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{2}{5}\cdot\left(\frac{13}{9}-\frac{4}{9}\right)\)
\(=\frac{3}{5}\cdot1+\frac{2}{5}\cdot1\)\(=\frac{3}{5}+\frac{2}{5}=1\)
_________________________________________
\(\frac{3}{4}\cdot x+\frac{4}{5}\cdot x=\frac{7}{10}\)
\(\left(\frac{3}{4}+\frac{4}{5}\right)\cdot x=\frac{7}{10}\)
\(\frac{31}{20}\cdot x=\frac{7}{10}\)
\(x=\frac{7}{10}:\frac{31}{20}\)
\(x=\frac{14}{31}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{145,7-290:5+0,3}{x:8+13}=4\)
=> \(\frac{145,7-58+0,3}{x:8+13}=4\)
=> \(\frac{88}{x:8+13}=4\)
=> \(x:8+13=88:4\)
=> \(x:8+13=22\)
=> x : 8 = 9
=> x = 9 x 8 = 72
Vậy x = 72
![](https://rs.olm.vn/images/avt/0.png?1311)
= \(\frac{145,7-58+0,3}{X:8+13}=4\)
=\(\frac{87,7+0,3}{X:8+13}=4\)
= \(\frac{90}{X:8+13}=4\)
X : 8 + 13 = 90 : 4
X : 8 + 13 = 22,5
X : 8 = 22,5 - 13
X : 8 = 9,5
X = 9,5 x 8
X = 76
\(\frac{145,7-290\div5+0,3}{x\div8+13}=4\)
\(\frac{88}{x\div8+13}=4\)
\(x\div8+13=88\div4\)
\(x\div8+13=22\)
\(x\div8=22-13\)
\(x\div8=9\)
\(x=9\times8\)
\(x=72\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
2,04 : ( x + 1,05 ) : 102 = 0,2
2,04 : ( x + 1,05 ) = 0,2 x 102
2,04 :( x + 1,05 ) = 20,4
x + 1,05 = 2,04 : 20,4
x + 1,05 = 0,1
x = 0,1 - 1,05
x = -0,95
Ps: Có j đó sai sai, lp 5 lm j có học số âm.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{88}{y:8+13}\)=\(\frac{88}{y:8}+\frac{88}{13}\)=
vô lý
ko có điều kiện của y
145,7 - 290 : 5 + 0,3
__________________= 4
x : 8 + 13