Question

The value of y is inversely proportional to the value of x. When y=42, x=6.

What is the value of y when x = 9?

Answer 1

Because $x$ and $y$ are inversely proportional, there is some constant $k$ such that

$xy=k$

Given that $y=42$ and $x=6$, we have

$k=6\times42=252$

So when $x=9$, you have

$9y=252\implies y=\dfrac{252}9=28$