75% of people say they shop online to save time, if 900 people were surveyed how many gave this anwser

If you are taking a percentage of a number, all you need to do is move that % behind a decimal point or convert it into lower terms, where 100%=1, 99%=0.99, and so on. Therefore, you will multiply 0.75 and 900 because 75%=0.75

0.75 x 900 = 675

675 people said they shop online to save time

The denominator would be 3