Answer:
Part a) [tex]350\ miles[/tex]
Part b) [tex]\$88.5[/tex]
Step-by-step explanation:
Let
x ----> the number of miles driven
y ----> the total cost
we know that
First Plan
[tex]y=0.09x+57[/tex] ----> equation A
Second Plan
[tex]y=0.11x+50[/tex] ----> equation B
Part a) For what amount of driving do the two plans cost the same?
Equate equation A and equation B and solve for x
[tex]0.11x+50=0.09x+57[/tex]
[tex]0.11x-0.09x=57-50[/tex]
[tex]0.02x=7[/tex]
[tex]x=350\ miles[/tex]
Part b) What is the cost when the two plans cost the same?
For x=350 miles
substitute in equation A or equation B (the cost will be the same)
[tex]y=0.09(350)+57[/tex]
[tex]y=\$88.5[/tex]