Remember, to find percentages, we can use the ratio
part percent
-------- = ----------
whole 100
Since 300 is the "part", 450 is the "whole", this gives the ratio:
Start with the given ratio
Multiply both sides by 100
Multiply
Simplify
So our answer is which is roughly 66.67
Now subtract this percentage from 100 to get
100-66.67=33.33
So the percent of discount is 33.33%