SOLUTION: Please help. I have a hard time with word problems. Here is the question. "An international calling plan charges a rate per minute plus a flat fee. A 10 minute call to France c

Algebra ->  Linear-equations -> SOLUTION: Please help. I have a hard time with word problems. Here is the question. "An international calling plan charges a rate per minute plus a flat fee. A 10 minute call to France c      Log On


   

Question 818153: Please help. I have a hard time with word problems. Here is the question.
"An international calling plan charges a rate per minute plus a flat fee. A 10 minute call to France cost $3.19. A 15 minute call to France costs $4.29. Write and solve a linear equation to find the cost of a 12 minute call to France.
Please help me.
Thanks
Found 2 solutions by dkppathak, richwmiller:
Answer by dkppathak(439) About Me  (Show Source):
You can put this solution on YOUR website!
An international calling plan charges a rate per minute plus a flat fee. A 10 minute call to France cost $3.19. A 15 minute call to France costs $4.29. Write and solve a linear equation to find the cost of a 12 minute call to France.
Answer
Let flat fee for call is X and rate per minute is Y
as per given conditions
X+10Y=3.19 (1)
X+15y=4.29 (2) by subtracting equations 1 from 2
-5y=-1.10
Y=1.10/5=0.22$
X+10y=3.19
X+10x0.22=3.19
X+2.2=3.19
X=3.19-2.2=0.99$
cost for 12 minute call
X+12Y
0.99+12x0.22=0.99+2.64=3.63$
Answer
flate fee is 0.99 $
minute rate is 0.22 $
fee for 12 minuter call =3.63$

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
we are looking for a linear equation in the form y=mx+b
the flat fee will B
the x will be the number of minutes
here we have two sets of x and y
(10, 319),
(15, 429)
find m the slope
429-319/15-10
110/5
22
y-319=22*(x-10)
y-319=22x-220
y = 22x+99

substitute 12 in for x to find y the cost of the phone call
y=264+99
y=$3.63