Answer: $66.1
Explanation:
Hi, to answer this question we simply have to substitute w= 15 in the formula and solve.
P=28+2.54w
Replacing w for 15 (units of water)
P = 28 + 2.54 (15)
Solving for P:
P = 28+ 38.1
P=$66.1
When he used 15 units of water, the monthly payment for Randy was $66.1
Feel free to ask for more if needed or if you did not understand something.