Step 1: Our output value is 50.
Step 2: We represent the unknown value with $x$.
Step 3: From step 1 above,$50=100\%$.
Step 4: Similarly, $x=30\%$.
Step 5: This results in a pair of simple equations:
$50=100\%(1)$.
$x=30\%(2)$.
Step 6: By dividing equation 1 by equation 2 and noting that both the RHS (right hand side) of both
equations have the same unit (%); we have
$\frac{50}{x}=\frac{100\%}{30\%}$
Step 7: Again, the reciprocal of both sides gives
$\frac{x}{50}=\frac{30}{100}$
$\Rightarrow x=15$
Therefore, $30\%$ of $50$ is $15$
