25% of 100 is 25 and 200 is twice as much as 100. So then double the 25 to 50.
You can also set up a proportion of 25%/100% = ?/200 and cross multiply and divide.
Another way is to manipulate the numbers. Instead of 25% of 200 you can say 200% of 25. 200% is the same as saying twice as much as the number so what is twice the number 25? 50!
