That's right. Taking a serious hit = being damaged, getting damaged.
From the conversation of A & B, you'll notice that 700 minus 350 does not equal 200. So in this case, Math is damaged.
Person B says, "You're saving, like, 200 bucks." But logically speaking, Person A is not saving 200 bucks. Given that 700 minus 350 is not 200. It's 350. So Person A is not saving 200 or