A cistern can be completely drained by a pipe in 6 hours. It can be filled by two pipes in 4 hours and 5 hours, respectively. How many hours will the empty cistern take to fill if all the pipes are running? If x is the time to fill it, which of the following equations could be used to solve for t?

4x + 5x - 6x = 1
4x + 5x = 20
15x + 12x - 10x = 60

to find the unit price, we must figure out the cost of one item (in this case one dish towel).   to do this, we divide the total price ($7.92) by the number of items bought (for this problem it is 8, because there are eight dish towels in one pack).  

$7.92/8 = $0.99

therefore, the unit price, or the price of one dish towel, is $0.99.

hope this !

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step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for

step-by-step explanation:

is their an equation anywhere i can take a   look at it and see if i am right.