Step 1: You want to remove the percent sign and then put the number over 100.
Step 2: If the percent is not a whole number then you want to multiply the top and bottom number by 10 but only for every number that comes after the decimal point.
Step 3: Always simplify if possible.
Examples:
43% = [tex]\frac{43}{100}[/tex]
78% = [tex]\frac{78}{100}[/tex] = [tex]\frac{39}{50}[/tex]
0.4% = [tex]\frac{0.4}{100}[/tex] = [tex]\frac{4}{1000}[/tex] = [tex]\frac{1}{250}[/tex]