One pipe fills a storage pool in 28 hours. A second pipe fills the same pool in 14 hours. When a third pipe is added and all three are used to fill the pool, it takes only
hours. Find how long it takes the third pipe to do the job.
The third pipe can fill the pool alone in
hours.

unless you made a typo, the answers are both a and c.

step-by-step explanation:

1.5/3 is .5 whereas 3/9 is .3333333 not proportional

22/33 is .66666 and 4/6 is also .66666 proportional

2/4 is .5 whereas 142/213 is .66666 not proportional

14/7 is 2 and 7/3.5 is also 2 proportional

you could've also checked it by doing this simple division:

if the larger fraction divides with the smaller fraction to equal 1, it is proportional. so let me show you what i mean:

when i divide 22/33 by 4/6 i get 1, so we know it is proportional, and it is the same with 14/7 and 7/3.5. now if i divide 3/9 by 1.5/3 i get .66666 so therefore we know it is not proportional.

there are many ways to do this so i wanted to show you some possible ways.

it would be 4 over -2 divided by -1 over 3.

if you want a solution it would be 4

you flip it so it would be 4/-2 divided by 3/-1 then it would be 12/3 and you would simplify it to 4