So he has to paint 255 m from the 280 m of paint he has First divide 255/280 to give you a decimal You should get .9107 Since this is in decimal form (out of 1) you want to get percentage which is out of 100 you multiply by 100 So .9107 times 100 This gives you the percentage which is 91.07% Now it says round to 1 decimal so it would be 91.1%