To differentiate \(\frac{5x}{x^5}\) with respect to \(x\), simplify the expression first:
\(\frac{5x}{x^5} = 5x \cdot x^{-5} = 5x^{1-5} = 5x^{-4}\)
Now, differentiate \(5x^{-4}\) using the power rule (\(\frac{d}{dx}[x^n] = n x^{n-1}\)):
\(\frac{d}{dx}[5x^{-4}] = 5 \cdot (-4) x^{-4-1} = -20x^{-5}\)
So, the derivative is \(-20x^{-5}\), or equivalently, \(\frac{-20}{x^5}\).

A ladder of fixed length \( h \) is to be placed along the wall such that it is free to move along the height of the wall.
Based upon the above information, answer the following questions:
(iii) (b) If the foot of the ladder, whose length is 5 m, is being pulled towards the wall such that the rate of decrease of distance \( y \) is \( 2 \, \text{m/s} \), then at what rate is the height on the wall \( x \) increasing when the foot of the ladder is 3 m away from the wall?