How many different three-letter "words" in LOGARITHM (for example, ORL, HLG, AOI) could you make using each letter no more than once in any one word? (There are three events: "select the first letter," "select the second letter," and "select the third letter." Find the number of ways each event can occur, and then figure out what to do with the three results.)

Suppose that Judy completes exercises on Monday. Since she doubles the amount of exercises every day, she will complete exercises on Tuesday, exercises on Wednesday, exercises on Thrursday and exercises on Friday.

So, she completed exercises.

She still has 7 problems left, which means that she did problems so far.

So, we have

Here's the number of exercises per day: