<p>I'm confused about how to approach this problem.</p>
<ol>
<li>A telephone company charges x cents for the first minute of a call and charges for any additional time at the rate of y cents per minute. If a certain call costs $5.55 and lasts more than 1 minute, which of the following expressions represents the length of the call, in minutes?</li>
</ol>
<p>(A): 555-x/y</p>
<p>(B): 555+x-y/y</p>
<p>(C): 555-x+y/y</p>
<p>(D): 555-x-y/y</p>
<p>(E): 555/x+y</p>
<p>bump bump…</p>
<p>I’d say just pick two values for x and y, figure out what it would be using the rule in the question, then see which answer choice is correct.</p>
<p>Let’s say x=30 and y=60, and you’re on the phone for 10 minutes. That would be 30+9*60=570 cents.</p>
<p>Now replace 555 with 570 in the answer choices, plug in x and y, and see which one ends up with 10. It happens to be C.</p>
<p>As a side note, be careful about order of operations when you’re typing out a problem. I figured out what you meant, but you should have put (555-x+y)/y and so on.</p>
<p>Let t be the time of the call, in minutes.</p>
<p>555 = x + y(t - 1)
555 = x + yt - y
555 - x + y =yt
(555 - x + y)/y = t</p>
<p>That isn’t exactly what C says, but I assume it’s what C is intended to say.</p>