Question

the ratio of females to total students in a math class is 18 to 30 what fraction and percent of the class is female

Answer 1

Add up 18 and 30.  You'll get 48.  Then 18/48 of the class is female.  Of course this could be simplified:  18/48 = 3/8.  Then 3/8 of the class is female and 5/8 is male.