Help, will medal and fan

Question

anonymous · Answer

https://gyazo.com/a9697d2a624b37b20541a4e93b2531a4

anonymous · Answer

^that's the problem

rhondasommer · Answer

What do you think?

anonymous · Answer

I dont really know how to set it up. I'm looking at the example but I dont think it's right. I'm getting 224/11

anonymous · Answer

I think 6:15pm maybe some one else can verify

anonymous · Answer

5pm to 8pm = 3 hours, in 3 hours the main pump will empty 3/4 tank, so how many hours for aux pump to empty 1/4 tank

mathmale · Answer

The first pump can empty the tanker in 4 hours.   We express this rate as$$\frac{ 1.tanker }{ 4.hours }$$

Similarly, the 2nd pumb can empty the tanker is 7 hours:$$\frac{ 1.tanker }{ 7.hours }$$

mathmale · Answer

add these two fractions together, being careful to find and use the LCD first.

Set the result equal to $$\frac{ 1.tanker }{ x.hours }$$   and solve the resulting equation for x (hours).    If 2 hours, tanker will be empty at 5:00 + 2:00 p.m., or 7:00 p.m.
If 3 hours, 8 p.m.

and so on.