\(\dfrac{5x}{4}=\dfrac{80}{120}\\ =>\dfrac{5x}{4}=\dfrac{2}{3}\\ =>5x.3=2.4\\ 5x.3=8\\ 5x=\dfrac{8}{3}\\ x=\dfrac{8}{3}:5\\ x=\dfrac{8}{15}\)
\(\dfrac{5x}{4}=\dfrac{80}{120}\)
\(\Rightarrow5x=\dfrac{4.120}{80}\)
\(\Rightarrow5x=6\)
\(\Rightarrow x=\dfrac{6}{5}\)