Olivia uses the work below to determine 55% of 720. Which explains the error in Olivia’s solution?

Question

Step 1: 
Step 2: 50% of 720 =  = 360
           10% of 720 =  = 72
             of 720) =  = 31
Step 3: 360 + 72 – 31 = 401 

Step 1: Olivia used percents that are not equivalent to 55%.

Step 2: Olivia incorrectly determined 50% of 720.

Step 2: Olivia incorrectly determined  of 10% of 720.

Step 3: Olivia subtracted  of 10% when she should have added.

Answer 1

Olivia said 1/2 of 72 was 31 when it should have been 36. So she incorrectly determined 1/2 of 10% of 720.

Answer 2

Answer: Step 1: Olivia used percents that are not equivalent to 55%.