Question

Let * be a binary operation, on the set of all non-zero real numbers, given by

$a*b=\frac{ab}{5}\mathrm{for}\mathrm{all}a,b\in R-\left\{0\right\}$

Write the value of x given by 2 * (x * 5) = 10.

Answer 1

$$\begin{gathered} \mathrm{Given}:\hspace{0.17em}2*\left(x*5\right)=10 \\ \mathrm{Here}, \\ 2*\left(\frac{5x}{5}\right)=10 \\ \Rightarrow 2*x=10 \\ \Rightarrow \frac{2x}{5}=10 \\ \Rightarrow x=\frac{10\times 5}{2} \\ \Rightarrow x=25 \end{gathered}$$