Question

An international calling plan charges a rate per minute plus a flat fee. a 10-minute call to france costs $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 phone call to france

Answer 1

Let flat fee for call be X and rate per minute be Y.
 So our equation for 10 minutes of call becomes X + 10Y = 3.19 ------------(1) And X + 15y = 4.29 for 15 minutes------------------------(2)
  Subtracting equations (2) from (1)
 5y=1.10
 Y = 1.10/5 = 0.22
  Substituting value for y In (1) we have
  X + 10(0.22) = 3.19
 X = 3.19 - 2.2 = 0.99
 Since we have obtained flat fee for call and rate per minute
  The cost for 12 minute call
 X + 12Y
 0.99 + 12(0.22)=3.63
 The fee for 12 minuter call =$ 3.63