68 of the 400 students take AP Chemistry. To find how many don't, subtract the total from the ones that do.

332 of the students don't take AP Chemistry. Divide 332 by 400 to get the decimal so that you can change it to a percent.

To change a decimal to a fraction, move the decimal point 2 places to the right and add a percent sign.

83% of the students don't take AP Chemistry