Rafael can choose plan a or Plan B for his long-distance charges. For each plan, cost (in dollars) depends on minutes used (Per month) as shown below.

a. Plan B; $4

b. 160 mins; Plan B

Step-by-step explanation:

a. Cost of Plan A for 80 minutes:

Find 80 on the x axis, and trave it up to to intercept the blue line (for Plan A). Check the y axis to see the value of y at this point. Thus:

f(80) = 8

This means Plan A will cost $8 for Rafael to 80 mins of long distance call per month.

Also, find the cost per month for 80 mins for Plan B. Use the same procedure as used in finding cost for plan A.

Plan B will cost $12.

Therefore, Plan B cost more.

Plan B cost $4 more than Plan A ($12 - $8 = $4)

b. Number of minutes that the two will cost the same is the number of minutes at the point where the two lines intercept = 160 minutes.

At 160 minutes, they both cost $16

The plan that will cost less if the time spent exceeds 160 minutes is Plan B.

answer: 12

step-by-step explanation:

step-by-step explanation: