In math: "of" means times
"is" means =
Since we have 2.5% of "what", we can replace what with a variable, say "y"
So now we can rewrite our equation...
2.5% * y = 2.21
We need to convert 2.5% to a decimal, so divide by 100 (or simply move the decimal 2 places to the left...
.025 * y = 2.21
Now we want to get the variable, y, by itself so we divide each side by .025
y = 2.21/.025
Now simplify by dividing
y = 88.4
2.5% of 88.4 is 2.21
