To answer all of these you make a fraction and it is structured like this: is/of=percent/100. So if it is asking for the of and you don't know if you just multiply 100 by the is and divide it by the percent. But if it is asking for the is then you multiply the percent by the of and divide it by 100
1. 400, 360/x=90/100 so you multiply 360 by 100 and get 36000 and divide it by 90
