firsst divide 8.75 in half to find the value of 100 vitamines which rounded is 4.38 then for 400 multiply 8.75 times 2 which is 17.5 then add the cost of 100 whuch is $21.88

Hello! So, the problem is saying that 200 vitamins cost $8.75, and that is what we know. We also know that we're going to be looking at the cost of 500 vitamins, but we don't know. The numbers presented can be put into a proportion, and that can help solve the problem. 200 to 8.75, and 500 to a number we don't know. I'm no sure if you familiar with the how to set up a proportion, but it's saying this number over this other number (which is a fraction) equals another fraction. Make sure that your numbers always match up, so your not saying vitamins over money equal money over vitamins. Use cross products, divide, and then you'll have your answer. For this problem, since yours solving for money, make sure to have two decimal points and a dollar sign. I hoped this helped, if you have any questions shoot me a question or message. Good luck!