Step-by-step explanation:
We know that y = 0.15x + b because you get charged $0.15 for every meter climbed, but we don't know b. Fortunately, we know that (3500, 645) belongs to the line, and therefore we have the following:
645 = 0.15 * 3500 + b
645 = 525 + b
120 = b, and therefore the equation is y = 0.15x + 120. Hope this helps!
