Solution
Part 3
For this case we have 6 different terms
Part 4
We can do the following:

Part 5
And we can simplify on this way:

Answer:
5 quartz would make the most sense, hope this helps
Step-by-step explanation:
Sorry I do not know. Sorry to let you down
It takes her (100 mi)/(50 mi/h) = 2 h to get to her destination. She has 1 h 40 min = 100 min for her 100 mi return trip.
.. (100 mi)/(100 min) = (60 mi)/(60 min) = 60 mi/h
She must return at the rate of 60 mph to complete the trip in 3 h 40 min.
-10/8 and + 15/8. Those should work.