. One pump can fill a tank of water in 5 hours. A second tank can fill the same tank in 4 hours. If both pumps are used together, how long will it take to fill the tank?
5/4 hours
9/20 hours
20/9 hours
4/5 hours

20/9

Step-by-step explanation:

5+4=9

4×5=20

I think. I'm a little rusty. hope this helps

20/9

Step-by-step explanation:

u gotta pay more attention in class this was an easy question

only 10/60 isn't equivalent

hope this : )

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.