Theory:

1. Finding a percentage of a given number:
To find the percentage of a given number, multiply the number by the require percent.
Let the number \(= x\)
Require percent \(= p\)\(\%\)
Percentage of given number \(= p\)\(\%\) of \(x\)
\(=\) p100×x
 
 
2. Finding the original number from its percent:
Let original number \(= x\)
Require percent \(= p\)\(\%\)
Obtained percentage \(= y\)
Now \(p\)\(\%\) of \(x = y\)
 
p100×x \(= y\)
 
\(x =\) yp×100
 
Number \(=\) Obtainedpercentagepercent×100
 
 
3. Finding how much percent one quantity is of another quantity:
To find what percent of one quantity is of the other quantity if two quantities are given, we proceed as:
Let \(a\) and \(b\) are two quantities and wee want to know 'what percent of \(a\) is \(b?\)'
 
Let \(x\)\(\%\) of \(a\) is equal to \(b\) then,
 
x100×a=bx=ba×100