\(\frac{x+1}{5}=\frac{x+4}{7}.\)
\(\Rightarrow\left(x+1\right).7=\left(x+4\right).5\)
\(\Rightarrow7x+7=5x+20\)
\(\Rightarrow7x-5x=20-7\)
\(\Rightarrow2x=13\)
\(\Rightarrow x=13:2\)
\(\Rightarrow x=\frac{13}{2}\)
Vậy \(x=\frac{13}{2}.\)
Chúc bạn học tốt!