Answer: 
Step-by-step explanation:
We have the equation 
where P represents the payment and w represents the amount of water used.
To calculate the monthly payment that corresponds to 12 units of water you must do 
in the main equation and solve for the variable P.
The signs mean greater than, less than or equal.
Answer:
hard question
Step-by-step explanation:
From 9 P.M. to 5 A.M. the temperature dropped 20°, making the rate over 8 hours, -2.5° Per Hour. By 5 A.M., the temperature is -5° since we had to do 15 - 20. From 5 AM to 5 P.M. is 12 hours so -2.5 x 12 = -30 making 30 how much the temperature dropped between 5 A.M. to 5 P.M. Finally, our last equation is -5 - 30 making -35 our answer.
