Hi...student here! On the magnification calculator available here on OptiBoard, I am not sure how to read the magnification percent, as there are two numbers given...any help out there?
OD +1.00 -0.25 180 BC 7.00D Cthickness 3.3mm VD 14mm

OS +3.50 -0.25 175 BC 9.00D Cthickness 4.3mm VD 14mm

The answer is supposed to be 3.4% magnification difference, but when I put the numbers into the calculator, I get...
OD Spectacle Magnification:
 3.0% / 2.6% × 180

OD Spectacle Magnification:
 7.9% / 7.5% × 175
I do not know how to come up with 3.4% regardless of number combinations!
Following this step I need to change some parameters, but if I can't read the answer correctly I can't even get to the next step!
*Just coming off of COVID and pneumonia, so I haven't been to class in a month..trying to catch up on discussion board posts from my professor!