Step 1: We make the assumption that 805. is 100% since it is our output value.
Step 2: We next represent the value we seek with $x$x.
Step 3: From step 1, it follows that $100\%=805.$100%=805..
Step 4: In the same vein, $x\%=402.5$x%=402.5.
Step 5: This gives us a pair of simple equations:
$100\%=805.(1)$100%=805.(1).
$x\%=402.5(2)$x%=402.5(2).
Step 6: By simply dividing equation 1 by equation 2 and taking note of the fact that both the LHS
(left hand side) of both equations have the same unit (%); we have
$\frac{100\%}{x\%}=\frac{805.}{402.5}$
100%
x%=
805.
402.5
Step 7: Taking the inverse (or reciprocal) of both sides yields
$\frac{x\%}{100\%}=\frac{402.5}{805.}$
x%
100%=
402.5
805.
$\Rightarrow x=50\%$⇒x=50%
Therefore, $402.5$402.5 is $50\%$50% of $805.$805..