To find 20 of 90, you need to calculate 20% of 90. To do this, you can use the following formula:
Percentage = (Part / Whole) * 100
In this case, the whole is 90, and you want to find out what 20% of that whole is. First, convert the percentage into a decimal by dividing by 100:
20% = 20 / 100 = 0.2
Now, multiply this decimal by the whole (90):
0.2 * 90 = 18
Therefore, 20% of 90 is 18.