The reduction in price is:
37.5
%
Original price
→
$40
Reduced to
→
$25
Writing this as a fraction of the original price we have
25/40
But this represents the final price.
What we need is the amount of reduction
The price has been reduced by
$40−$25=$15
So as a fraction of the original price the reduction is:
15/40
Converting this to a percentage
Let the unknown value be
x
15/40=x/100
Multiply both sides by 100
15/40×100 = x × 100/100
But 100/100= 1
x = 15/40 × 100 = 37 1/2→37.5 giving: 37.5/100 = 37.5 × 1/100 = 37.5%