A telephone company charges x cents for the first minute of a call and

I am always cautious while marking (A) as my answer. Not because the probability of it being the answer is low, but because if the question has a trap people could fall for, then the question maker will set (A) as that particular lucrative option. (Hell, I do that when I make questions! Kind of a bait!) So I like to double check especially if it seems too easy.

The logic of (555 - x)/y was perfectly valid. The only missing point was that these are the (n -1) additional minutes. You did not account for the 1st minute. So total time will be (555 - x)/y + 1 which is the same as option (C): (555 - x + y)/y

And yes, parentheses will definitely be there in the exam in such a question. 555 - x + y/y = 555 - x + 1 (Since it didn't make any sense here, it was obvious that there are parentheses in the options). Rest assured, there will not be any ambiguity in the actual exam.

Since x and y are in cents, we should start by expressing $5.55 in cents, which is 555 cents. We can then create the following equation where t = the length of the call, in minutes:

555 = x + y(t - 1)

555 - x = yt - y

555 - x + y = yt

(555 - x + y)/y = t

Answer: C

Given that 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. And If a certain call costs $5.55 and lasts more than 1 minute, then what is the value of length of the call

Let call duration be (1 + t) mins

=> Charge will be $X (for first min) + $y * t (for t additional mins)
= $X + $yt = $555 (given)
=> t = \(\frac{555 - X}{y}\)

=> Total call duration = 1 + \(\frac{555 - X}{y}\) = \(\frac{555-x+ y}{y}\)

So, Answer will be C
Hope it helps!