It always amazes me when tutors bring more complicated terms into a question for no reason. If you understood all that nonsense you wouldn't need a tutor!
In this question, you have 2 pipes out of commission so forget about them. You have 6 working pipes out of 8.
That means the only numbers involved are 8, 6, and 27.
The next thing to understand is that if it takes 8 pipes 27 minutes to fill a tank, and some of them go out, the job is going to take longer, right? That means if you come up with an answer that's less than 27 minutes, you did something wrong.
What's the easiest way to apply the above three numbers to make 27 fractionally bigger? Multiply it by the fraction 8 over 6.
If you simplify at this point, the arithmetic is easier. Eight over six is the same as four over three. How do you multiply something by 4 over 3? Multiply by 4 (which means double it twice) and then divide by 3.
Your answer will come out to 36 minutes.
If you must, must, must express the steps in a formal way, you can say:
x = ( n / n - r) * m
n = the number of pipes at the start;
r = the number of pipes lost;
m = number of minutes for n pipes;
x = the number of minutes for r pipes,
And wow, you look smart.