This is the dumbest thing I've read.
First is that woman doing math. I've never seen a successful woman mathematician. In university, all the "smart girls" in engineering and math departments had sumps who did their work for them.
But mainly, even if the math is all correct, the price gap is either genuinely needed as the products are not the same or women are stupid enough to pay more for the exact same item that men get.
It could be that the "women's" razors need extra steps in manufacturing to make theshaving experience less irritating. Also women tend to shave smaller, cramped places when compared to men. This might mean the blades, section that reduces irritation or handles must be designed specifically for women. All these cost development time and production. This could apply to other things that she mentioned like vitamins and skincare.
Similar reasoning can apply to something like clothing. Women care a lot more about appearance so even if the material used for clothes are comparable, a lot more thoughts must go into the design of the clothing.
The other point is that women are dumb and just fall for marketing gimmicks. Just like children demanding "children's meal" at a restaurant, women see women's product and think it must be designed especially for them. Maybe the razors do cost exactly the same. But women see pink colour and think it's better.
All these weird "math" could have been avoided if she just shut up and bought the men's product. But she won't because she FEELS like she should be buying womens product, just like the marketing told her to.
Sharia law cannot come fast enough to the west.