Question 55141
$0.96 the first minute and $0.72 thereafter! What kind of 1-900 number is this! Whatever...on to the math. 

Let's say that {{{f(t)}}} is a function that states the cost of this phone call after {{{t}}} minutes.

{{{t}}} is the number of minutes you've been on the phone. Let's figure out what {{{f(t)}}} should be. 

Well, we know that just picking up the phone costs us $0.96. After the first minute, we pay $.72 per minute. 

Ok...in mathspeak, thats:
{{{f(t)=0.96 + 0.72t}}}

We want {{{f(t)<=6}}} so lets do that:

{{{0.96+0.72t<=6}}}

Ok...I think we've done what we're asked.