SOLUTION: a class has 21 boys. the girls make up 2/5 of the class. how do i find the total number of pupils in the class

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Question 947756: a class has 21 boys. the girls make up 2/5 of the class. how do i find the total number of pupils in the class
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

let the total number of pupils in the class be x
x=boys%2Bgirls
if a class has 21 boys,
and the girls make up %282%2F5%29 of the class which means the girls make up %282%2F5%29x, then

x=21%2B%282%2F5%29x .........solve for x
x-%282%2F5%29x=21
5x%2F5-%282x%2F5%29=21
%285x-2x%29%2F5=21
3x%2F5=21
3x=21%2A5
3x=105
x=105%2F3
x=35 -the total number of pupils in the class