Let x = the number of total students in the class
Convert the percent into a decimal by moving the percent sign two places to the left and change the percent sign into a decimal point.
60% = 0.6
Then 0.6x = the number of girls in the class
Then 0.6x + 30 = the total number of students in the class
0.6x + 30 = x
Solve for x.
0.6x + 30 = x
0.6x = x - 30 <-- Subtract both sides by 30
-0.4x = -30 <-- Subtract both sides by x
x = 75
Now we have the total number of students in the class.
60 percent of the students are female.
0.6 * 75 = 45
So, C 45 is the answer.
