Write each percent as a fraction in simplest form:
45%
62%
68%
2%

Percentages are really just fractions out of 100. So 45% is really just 45/100. If you want to find the lowest fractions, you have to break each number up into prime factors and see which overlap. So:

45 = 9x5
     = 3 x 3 x 5
100 = 2 x 50
       = 2 x 5 x 10
       = 2 x 5 x 2 x 5

So 45/100 = 3x3x5/2x2x5x5

Now because there's a 5 on both sides, we can cancel down. If we do, that leaves us with

3x3/2x2x5

Which is 9/20