Help on this problem

<p>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 elngth of the call, in minutes?</p>

<p>If the length of the call is m minutes, then the cost of the call is x cents for the first minute and y cents for the m-1 minutes after the first minute. Thus, the cost, in cents, of the call is x+(m-1)y. The cost of the call is 555 cents, so 555=x+(m-1)y=x+my-y. Therefore it is my=555-x+y, so 555-x+y/y</p>

<p>WHY is it that when y charges additional time for every minute you call, you do m-1? If it costs MORE, aren't you supposed to ADD? Help</p>

<p>The cost of the additional minutes after the first is y(m-1) because the first minute is already counted in the "x cents for the first minute." hence, in a 30 minute call, 1 minute is included for the x cents, and the cost of the remaining minutes is y(30-1) = y(29).</p>