need help algebra 2 its urgent plz

Question

Madison determined that the function f(x)=3x+2/4 represents the cost of texting on her current cell phone plan, where x represents the number of texts.  She discovers that using the inverse function to solve for x=36, she can predict how many texts she can use for $36. Explain to Madison how to accomplish this, using complete sentences. You may show any algebraic work necessary to support your explanation. 

Answer 1

Hello, Kacim,

May I assume that when you state x = 36, that you mean f(x) = 36? I assume so in my response:

The function f(x) = 3x + 2/4 tells us the cost of texting based on the number of texts, x. 3x means that each text costs $3 (!). The 2/4 represents a fixed cost that is part of the plan. It's not clear if this is per day, week, month, year, etc. But we'll assume it is $0.50 for the period in which Madison will spend $36. We need to deduct the $0.50, leaving $35.50 to spend on texts.

$36.00 = 3x + $0.50

$35.50 = 3x

x = 11.83

Madison can only make 11 texts for a total of ($3*11=$33). The remaining $2.50 will only cover 0.83 of a text, so we need to round down to 11.

Bob