Write and solve a linear equation to find the cost of a 12-minute call to France.

Question

An international calling plan charges a rate per minute plus a flat rate fee. A 10-minute call to France costs $3.19. A 15-minute call to France costs $4.29. 

Answer 1

r = rate per minute

f = flat rate

 

 

for the 10 minute call

 

f + 10r = 3.19

 

for the 15 minute call

 

f + 15r = 4.29

 

Subtract the top equation from the bottom

 

5r = 1.10

r = 0.22

 

The per minute rate is 22 cents.