Use the geometric mean for right triangles here. Like this

. Cross multiply to get

, and

. That simplifies down to

. Pull out the 9 as a perfect square of 3 and you're left with

, first choice above.
Answer:
1000000
Step-by-step explanation:
100*2.2=220
80*2=176
220+176=396
So the two trains will take 2.2 hours so that they are 396 miles apart.
3/8 of a fraction is the amount of water that was split