Answer:
Please see the attached file for the complete answer.
Step-by-step explanation:
The formula of a slope:

We have the points (look at the picture) (0, 1) and (-2, -2). Substitute:

Base should look like __ from above.
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If you were to look at the bottom of the stacked cubes from the bottom it should look like __.
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Converting 1 hour and 15 minutes to minutes only, its 75 minutes. 75 - 54 is 21. So, Martin has 21 minutes left to finish.