Please help me understand the following

8. [10 points] You work for the California Department of Water Resources. Your job is to predict the quantity of water demanded in Los Angeles in 2023 (H20 measured in acre-feet). Based on historical data you estimate the following regression: H20 = a + 31 x price + 32 x population + 83 x rainfall + E and the results are Coeff. T-stat a 94,000 1.25 B1 4,800 4.31 B2 0.6 2.77 B3 -4,000 3.51 Predict water consumption in Los Angeles, which has a population of 4 million and is expected to get 10 inches of rainfall. The expected price of one acre-foot of water is $55