`a)x/4=9/10`
`x=9/10. 4`
`x=18/5`
`b)x/24=6/x`
`x.x=24.6`
`x^2=144`
`x^2=(+-12)^2`
`x=+-12`
`c)\frac{5-2x}{3}=\frac{4x-1}{5}`
`<=>-5(5-2x)=3(4x-1)`
`<=>-25+10x=12x-3`
`<=>10x-12x=-3+25`
`<=>-2x=22`
`<=>x=-11`
`d)\frac{10-2x}{6}=\frac{27}{5-x}`
`<=>\frac{2(5-x)}{6}=\frac{27}{5-x}`
`<=>\frac{5-x}{3}=\frac{27}{5-x}`
`<=>(5-x)(5-x)=3.27`
`<=>(5-x)^2=81`
`<=>(5-x)^2=(+-9)^2`
`<=>`$\left[\begin{matrix} 5-x=9\\ 5-x=-9\end{matrix}\right.$
`<=>`$\left[\begin{matrix} x=-4\\ x=14\end{matrix}\right.$
