A cell phone plan charges $45.50 a month, plus $0.05 per text message. Write and graph an expression to find how many text messages, x, can be sent while still keeping the monthly bill under $60.

We can write this in slope-intercept form, or [tex]y=mx+b[/tex]. Since x is defined as the #of text messages, and 0.05 is the cost of a text message, 0.05 will be m. 45.5 is the base price, or the y-intercept, so it will be b.

Plugging in these numbers, we get [tex]y-0.05x+45.5[/tex]

now we make y = 60, since that is the total amount they have

[tex]60=0.05x+45.5\\14.5=0.05x\\x=290[/tex]

So, they can send 290 messages for 60, but they need the bill under 60, so 1 text message less will be 289, and that's enough.

A cell phone plan charges $45.50 a month, plus $0.05 per text message. Write and graph an expression to find how many text messages, x, can be sent while still keeping the monthly bill under $60.​

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A cell phone plan charges $45.50 a month, plus $0.05 per text message. Write and graph an expression to find how many text messages, x, can be sent while still keeping the monthly bill under $60.