Let's set up an equation to solve this problem. In the question it says 85% of some number. Now in mathematics, the word 'of' can mean multiply in certain contexts.
And '... of what number' is some unknown. Which we will be represented by the variable x.
The word 'is' in mathematics can mean equal in certain contexts.
Before we build our equation, turn the percent into a decimal by moving the percent sign two places to the left and making it into a decimal point.
85% = 0.85
Now we have our equation.
0.85x = 38.25
Solve for x.
To solve for x, get the variable on one side the equation by itself and everything else on the opposite side.
Divide both sides by 0.85.
0.85x / 0.85 = 38.25 / 0.85
x = 45
So, 45 is the answer.