suppose a 5-minute overseas call costs $5.91 and a 10-minute call costs $10.86 what is the slope

Answer 1

(M,C) = (5,5.91) and (10,10.86)

slope = rise over run = (10.86-5.91)/(10-5) = 4.94/5 = 0.988

that's plotting minutes on the x axis and cost in dollars on the y axis

C=.988M + b

10.86 = .988(10) + b

b = 10.86-9.88 = 0.98

the line is

C=0.988M + 0.98

There is a 98 cent charge even if you use zero minutes, then they charge 98.8 cents per minute

It's about a dollar a minute, plus a one dollar charge just for calling at all