Question

Let $\ast$ be a binary operation on the set of all non zero real numbers, given by $a\ast b=\frac{ab}{5}\forall a,b\in R-\left\{0\right\}$, find the value of $x$, given that $2\ast (x\ast 5)=10$

Answer 1

$2\ast (x\ast 5)=10$

$\Rightarrow 2\ast \left(\frac{x.5}{5}\right)=10$

$\Rightarrow 2\ast \left(x\right)=10$

$\Rightarrow \frac{2.x}{5}=10\Rightarrow x=25$