Question

tìm số tư nhiên n ? biết :23+n/40+n = 3/4

 

Answer 1

\(\frac{23+n}{40+n}=\frac{3}{4}\)

\(\Rightarrow4\left(23+n\right)=3\left(40+n\right)\)

\(\Rightarrow92+4n=120+3n\)

\(\Rightarrow\left(92+4n\right)-\left(92+3n\right)=\left(120+3n\right)-\left(92+3n\right)\)

\(\Rightarrow n=28\)

Answer 2

Ta có: \(\frac{23+n}{40+n}\)=\(\frac{3}{4}\)\(\Rightarrow\)4(23+ n)= 3(40+ n)\(\Rightarrow\)92+ 4n= 120+ 3n\(\Rightarrow\)4n- 3n= 120- 92\(\Rightarrow\)(4- 3)n= 82\(\Rightarrow\)n= 82.

Vậy n= 82 để  \(\frac{23+n}{40+n}\)=\(\frac{3}{4}\).