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Answer:
Paul is using 1 grid = 100%; Rebecca is using 2 grids = 100%
Step-by-step explanation:
We assume that a full grid and half of another are shaded.
If 1 grid is taken to be 100%, then the total amount shaded is 100% +50% = 150%, as Paul says.
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If the two full grids are taken to be 100%, then the full shaded grid is 50% of the total, and the additional half-shaded grid is 25% of the total. That makes a total of 50% +25% = 75% of the total being shaded, as Rebecca says.
