Answer:
The third option, -1/2(30) = -15
Step-by-step explanation:
If it decreases by 1/2, we know it has to be -1/2, and the days we are given are 30. We need to multiply -1/2 by 30 in order to find the water level after 30 days, which would be -15 (inches?) I hope this helped.
1 5/7
the 3rd one hope that helped
113-2t√17