There are 32 students in cody’s class. if there were twice as many girls in the class, the total number of students would be 45. how many girls are in cody’s class?

The amount of girls and boys in the class can be found by subtracting the total from the second total. 45 - 32 = 13. 13 is the amount of girls in Cody's class. This is a simple way of finding it, all you do is take off the amount of extra students, because it was doubled, you can just use the number taken off. 

Hope you understand and hope this helps. Good Luck!