Hi Jack,
To answer this question, you need to convert the 22/25 into a percentage. If you're not using a calculator, you need to divide 25 into 22.
__________
25) 22.00
Once you get an answer, which will be in decimal format (hint, the number will be less than 1), you move the decimal over 2 places to the right to get the percentage.
Once you get that number, subtract the smaller number from the larger number to get the difference in percentage grade.
I hope this helps! Feel free to comment if you need updating. If you need additional help, I'm available to tutor through video conference. Good luck!