\(\Leftrightarrow\sqrt{5x}=\dfrac{7}{4}\)
=>5x=49/16
=>x=49/80
\(1\dfrac{3}{4}-\sqrt{5x}=0\\ =>\dfrac{7}{4}-\sqrt{5x}=0\\ =>\sqrt{5x}=\dfrac{7}{4}\\ =>\left(\sqrt{5x}\right)^2=\dfrac{49}{16}\\ =>5x=\dfrac{49}{16}\\ =>x=\dfrac{49}{16}:5\\ =>x=\dfrac{49}{80}\)