SOLUTION: when making a telephone call using a calling card, a call lasting 6 minutes costa $2.75. a call lasting 16 minutes costs $6.75. find a linear function that relates the cost,C, of

Algebra ->  Equations -> SOLUTION: when making a telephone call using a calling card, a call lasting 6 minutes costa $2.75. a call lasting 16 minutes costs $6.75. find a linear function that relates the cost,C, of       Log On


   

Question 411614: when making a telephone call using a calling card, a call lasting 6 minutes costa $2.75. a call lasting 16 minutes costs $6.75. find a linear function that relates the cost,C, of a making a call to the length, x, of the call, treating the length of the call as the independent variable
Answer by ewatrrr(24785) About Me  (Show Source):
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Hi

(16,6.75)

( 6,2.75) m = 4/10 = 2/5   |point-slope formula, m+=%28y%5B2%5D+-+y%5B1%5D%29%2F%28x%5B2%5D+-+x%5B1%5D%29

Using the standard slope-intercept form for an equation of a line y = mx + b 

 where (2/5) is the slope and b the y-intercept.  

 C = (2/5)x + b   |using ordered pair (6,2.75) to solve for b

 2.75 = (2/5)*6 + b

 2.75-2.4 = b

      .35 = b

 C =(2/5)x + .35



 CHECKING our Answer***

 $6.75 = (2/5)16 + .35 = 32/5 + .35 = 6.4 + .35 = $6.75