Question 290676
not miscellaneous category but travel and distance. Did you notice the question is about 2 boats traveling and the distance apart?
r*t=d
We will take this in two parts. 
It is best to draw a diagram of what happened.
first meeting
boat a went 500 meters
boat b went x-500 meters

second meeting
boat a went x +300 meters
boat b went x +x-300
The key is that for both legs of the trip the times are the same since they start and end together.

a*t=500
b*t=x-500
t=500/a
t=(x-500)/b

500/a=(x-500)/b
a*T=x+300
b*T=x+x-300
T=(x+300)/a
T=(2x-300)/b

Now we have eliminated the times
(x+300)/a=(2x-300)/b
500/a=(x-500)/b
We have three unknowns with two equations so we can't solve for a,b and x
We can get a ratio of a and b
x =1200 meters from A to B
b=7a/5