Answer each point from the exercise separately. to see if the number is reasonable, divide it by 30 as there are around 30 days each month and see if this number of messages send or received per day is a lot.
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Practice makes perfect
We will answer each of the points from the exercise separately, which will help us form a plan for this problem.
What information do you know? What information do you need?
We know that our cell phone plan costs $39.99 per month, and that we have to pay $0.15 for each text message we send or receive. We also know that we have at most $45 to spend on our cell phone.
What we need is an expression that will give us the total cost for our cellphone per month.
What inequality can you use to find the maximum number of text messages that you can send or receive?
Let x be the number of text messages we send or receive per month. Each message costs $0.15, and our total cellphone plan costs $39.99. Then, an expression for the total cost per month is:
0.15+39.99x.
Since we have at most $45 to spend, the expression has to be less than or equal to 45, which gives us the following inequality:
0.15x+39.99 ≤ 45.
What are the solutions of the inequality? Are they reasonable?
To find the solutions of the inequality, let's isolate x.
