Answer: y = 64
Step-by-step explanation:
[tex]$Given, \\$y$ is directly proportional to $x$ \\$\Rightarrow y \propto x$ (Note: ' $\alpha$ ' be proportion/various sign) \\$\Rightarrow y=k x$ ( $k$ be the constant) \\$\therefore y=k x-$ (1)[/tex]
[tex]$Given $y=40$ when $x=10$.So, substitute $y=40 \ \& \ x=10$ in (1) we get,$\begin{aligned}&\Rightarrow 40=k(10) \\&\Rightarrow 10 k=40 \\&\Rightarrow k=\frac{40}{10} \text { (divide '10' both sides) } \\&\Rightarrow k=4\end{aligned}$[/tex]
[tex]$Put $k=4$ in (1) we get,$y=4 x$We substitute $x=16$ in (2) we get$\begin{aligned}y &=4(16) \\\Rightarrow y &=64 \\\end{aligned}$[/tex]
