Here's a tip, the multiplication symbol can also be represented by the word "of" so you equation is 80% of 200. You can put that in a calculator, or if you want to do it on paper, just know this: % symbol means that it is divided by 100. So, You can put in a calculator 80% x 200 or you can do the math on paper, .80 x 200. Using this formula, you can find your answer.
Also , since we are using equivalent ratio , we will look for a way to write 200 in order to have equivalent of 100. That is 200 is the same as 100 x 2