Help with my math homework ( HSPA Review)

José, a traveling salesman, wants to buy a cellular phone to use while he is on the road. His employer allows him $50.00 a month for this expense. He researches different options. Company A's rate is a minimum charge of $15.00 per month and $2.00 per minute of usage. Company B's rate is $17.00 per month and $1.50 per minute of usage.

A) write two equations representing each company's month rate in terms of minutes.
B) for his $50.00 per month allowance, how many minutes of usage will he get from each company?
C) which company permits more usage and by how many minutes?
D) Jose contracts with company B. In march, Jose uses his cellular phone for 19 minutes. What was his monthly bill for march ? Explain the process used to arrive at his answer.

Let x = minutes of charge per usage
A)
Company A
Cost = 15 + 2x
Company B
Cost = 17 + 1.5x
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B) Company A. Minutes of usage: 50 = 15 + 2x so x = 17.5 minutes
...Company B. Minutes of usage: 50 = 17 + 1.5x so x = 22 minutes
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C) Most usage by company B by 22 - 17.5 minutes = 4.5 minutes
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D ) Using Company B cost = 17 + 1.5*19 = 17 + 28.5 = 45.5
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A) A(t) = 15.00 + 2.00t, where t represents the minutes used that month
B(t) = 17.00 + 1.50t

B)
Solve A(t) = 15.00 + 2.00t = 50.00
Solve B(t) = 17.00 + 1.50t = 50.00

C) Compare the solutions you got in B.

D) March expense = B(19)

What? You expect me to do all the work?