First, change the percent to a decimal by moving the decimal two places to the left:
16 1/4 % = 16.25% = .1625
Now place it in decimal form. You put this number over 10,000 because it has 4 digits to the right of the deimal (10,000 has four 0's)
1625/10,000
Now let's simplify it by dividing the top and bottom by 125
1625 divided by 125 ......= 13
--------------------------------- = --------
10,000 divided by 125 ....= 80