Question

exercise 1
john’s father asked him to compare several different cell phone plans and identify which plan will be the least expensive
for the family. each phone company charges a monthly fee, but this fee does not cover any services: phone lines,
texting, or internet access. use the information contained in the table below to answer the following questions.

cell phone plans

name of plan	monthly fee (includes 1,500 shared minutes)	price per phone line x	price per line for unlimited texting y	price per line for internet access z
company b	$90	$15	$10	$20
company c	$200	$10	included in monthly fee	included in monthly fee

all members of the family may not want identical plans; therefore, we will let x represent the number of phone lines,
represent the number of phone lines with unlimited texting, and z represent the number of phone lines with internet
access.

expression

company a _______________

company b _______________

company c _______________

Explanation:

Step1: Analyze Company A's Costs

The monthly fee for Company A is $70. The price per phone line is $20 (for \( x \) lines), per unlimited texting line is $15 (for LXI1 lines), and per internet access line is $15 (for \( z \) lines). So the total cost is the sum of the monthly fee and the costs for each service.
Expression: \( 70 + 20x + 15y + 15z \)

Step2: Analyze Company B's Costs

Company B has a monthly fee of $90. Price per phone line is $15 (for \( x \) lines), per unlimited texting line is $10 (for LXI1 lines), and per internet access line is $20 (for \( z \) lines). Sum these to get total cost.
Expression: \( 90 + 15x + 10y + 20z \)

Step3: Analyze Company C's Costs

Company C's monthly fee is $200. Price per phone line is $10 (for \( x \) lines). Unlimited texting and internet access are included in the monthly fee, so we only add the cost for phone lines to the monthly fee.
Expression: \( 200 + 10x \)

Answer:

Company A: \( \boldsymbol{70 + 20x + 15y + 15z} \)
Company B: \( \boldsymbol{90 + 15x + 10y + 20z} \)
Company C: \( \boldsymbol{200 + 10x} \)