Answer:
73 inches
Step-by-step explanation:
First you calculate the the change separately. The change for 4 weeks would be...
Evaporation: -3x4=-12
Adding water (every 2 weeks): 5x2=10
Then you add -12 + 10 = -2. There is a -2 inches change during 4 weeks. Finally you subtract 75 -2 = 73 inches.
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