Question 818153
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$