Question

Help me,
Best answer rewarded,
screencap in comments.

Answer 1

first you have to try and get rid of the fraction part by multiplying throughout by the denominator of the fraction, x in this case

Answer 2

\[c-1 =cdx-dx\]

factor out dx.\[c-1=dx(c-1)\]

divide both sides by c-1 so that,

\[\frac{ c-1 }{ c-1 }=\frac{ dx(c-1) }{ c-1}\]

hence,
\[1=dx\]

and

\[\frac{ 1 }{ d } = x\]