Yup you are on the right track. You are going to have two more boxes, one for each variable being set and then in your while loop you are going to have a diamond with the condition
numberLaps <> 0 in it. You will have a line down to a series of boxes for your calculations. After your last calculation draw an arrow to the side and back up and pointing to the arrow that is going back down into your diamond. Out the side of the diamond you are going to draw an arrow to the side and down to the first box after the loop (where you calculate averageMPG). This one represents when the condition is false (that is when your numberLaps DOES equal zero).
Example...
Where you have your sequences you are going to have multiple boxes for your calculations. Then after they are all done, back to the top of the loop.
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