Question 268626
You are given 2 points in the form (x,y)
where x is minutes and y is the monthly bill
The 2 points also give you the slope of the line
as (change in y)/(change in x)
Use the point slope formula
{{{(y - y[1])/(x - x[1]) = (y[2] - y[1])/(x[2] - x[1])}}}
(x1,y1) = (120,53.95)
(x2,y2) = (412,68.55)
{{{(y - 53.95)/(x - 120) = (68.55 - 53.95)/(412 - 120)}}}
{{{(y - 53.95)/(x - 120) = 14.6/292}}}
{{{y - 53.95 = .05*(x - 120)}}}
{{{y - 53.95 = .05x - 6}}}
{{{y = .05x + 47.95}}}
Even when there are no minutes there is a charge
of $47.95 for each monthly bill
She pays 5 cents per minute