The first step to solve this problem is to convert 1h 30min into just minutes. since there are 60 minutes in 1 hour you take 60 and add it ot the 30 extra minutes to get a total of 90.
Now, this question is asking you to find how many calories <u>per</u> minute she burns. When you are asked to find ___ per___ all you have to do is divide the first number by the second one. In this case you will divide calories by minutes.
