Bài  3: Rút gọn rồi tính:

a, 3/7 + 40/25 = 71/35         

b, 24/30 + 18/63 = 38/35             

c, 5/4 + 10/80 = 11/8

ko biết bạn ơi

\(\frac{2133}{2136}+x=1\)

\(x=1-\frac{2133}{2136}=\frac{2136}{2136}-\frac{2133}{2136}\)

\(x=\frac{3}{2136}=\frac{1}{712}\)

#Fox

a, \(\frac{3}{7}+\frac{40}{25}=\frac{3}{7}+\frac{8}{5}=\frac{15}{35}+\frac{56}{35}=\frac{71}{35}\)

b, \(\frac{24}{30}+\frac{18}{63}=\frac{4}{5}+\frac{2}{7}=\frac{28}{35}+\frac{10}{35}=\frac{38}{35}\)

c, \(\frac{5}{4}+\frac{10}{80}=\frac{5}{4}+\frac{1}{8}=\frac{10}{8}+\frac{1}{8}=\frac{11}{8}\)

#Fox

A) \(\frac{3}{7}+\frac{40}{25}=\frac{3}{7}+\frac{8}{5}=\frac{15}{35}+\frac{56}{35}=\frac{71}{35}\)

B) \(\frac{24}{30}+\frac{18}{63}=\frac{4}{5}+\frac{2}{7}=\frac{28}{35}+\frac{10}{35}=\frac{38}{35}\)

C) \(\frac{5}{4}+\frac{10}{80}=\frac{5}{4}+\frac{1}{8}=\frac{10}{8}+\frac{1}{8}=\frac{11}{8}\)

_HT_

TL: 

a) x - 1/4 = 5/3       

    x         = 1/4 + 5/3 

   x          = 4/6  

b) x - 2/3 = 1/2 

   x          = 2/3 + 1/2 

   x          = 7/6 

k cho mình 

HT

a, X = 5/3 + 1/4 

x = 20/12 + 3/12

X = 23/12

b, X = 1/2+ 2/3

X = 3/6 + 4/6

X = 7/6

a, \(x-\frac{1}{4}=\frac{5}{3}\)

 \(x=\frac{5}{3}-\frac{1}{4}=\frac{20}{12}-\frac{3}{12}\)

\(x=\frac{17}{12}\)

b, \(x-\frac{2}{3}=\frac{1}{2}\)

\(x=\frac{1}{2}+\frac{2}{3}=\frac{3}{6}+\frac{4}{6}\)

\(x=\frac{7}{6}\)

#Fox

\(A.X-\frac{1}{4}=\frac{5}{3}\)

\(X=\frac{5}{3}-\frac{1}{4}=\frac{20}{12}-\frac{3}{12}\)

\(X=\frac{17}{12}\)

\(B.X-\frac{2}{3}=\frac{1}{2}\)

\(X=\frac{1}{2}+\frac{2}{3}=\frac{3}{6}+\frac{4}{6}\)

\(X=\frac{7}{6}\)

_HT_

\(\frac{3\times145+3\times55}{6\times215+6\times85}\)

\(=\frac{3\times\left(145+55\right)}{6\times\left(215+85\right)}\)

\(=\frac{3\times200}{6\times300}\)

\(=\frac{600}{1800}=\frac{1}{3}\)

#Fox

đáp số là 16/60; 17/60; 18/60 ; 19/60