Problem Solving (PS) | When a subscription to a new magazine was purchased for m months, the

Hi I too am confused about the wording.

The question says "the publisher offered a discount of 75 percent off the regular monthly price" - to me this seems to be short hand for "the publisher offered a 75% discount off of the regular monthly price." The discounted price is thus 0.25 x regular price, or 0.75 off of the regular price.

My confusion stems from the word 'off' (or in other words 'off of') vs 'of'

Is this correct??