\(x+10=80\)

\(^{ }\Rightarrow x\)  \(=80-10\)

 \(\Rightarrow x\)   \(=70\)

1/6 giờ < 1/5 giờ 

Mí bạn k mk nha !!!!! Làm ơn làm phước nhá

Ta có:  \(\frac{1}{n}-\frac{1}{n+1}=\frac{n+1-n}{n\left(n+1\right)}=\frac{\left(n-n\right)+1}{n\left(n+1\right)}=\frac{1}{n\left(n+1\right)}\)

Vì \(\frac{1}{n\left(n+1\right)}=\frac{1}{n\left(n+1\right)}\Rightarrow\frac{1}{n\left(n+1\right)}=\frac{1}{n}-\frac{1}{n+1}\) ĐPCM