When you change the fraction 45/54 into a percent, you get 83.33%. This is the same value written in a different way, so you can think of it as the same amount expressed with a “%” sign.
The fraction 45/54 can be simplified by dividing both the top and bottom numbers by 9, which gives 5/6. Knowing that 5/6 is close to a whole number helps you see why the percent is high, just under 100%.
Both forms—83.33% and 5/6—show the same relationship between the parts and the whole. You can use whichever one works best for the problem you are solving.