ElectricPavlov

I will assume the slower one is in front  o/w they will never meet

the 20 m/s one is traveling 10 m/s faster than the other one and will eat up that 500 m separation in 500 m /10 m/s= 50 seconds

I will assume bird flies 5 m    THEN gets backed up 2 m

  bird gains   3 m per day

   after 98 days bird will be at 294

     on day 99 bird will REACH 299 and get backed up to   297

        on day 100   bird will reach destination

Where is the diagram?? 

I think we need the dimensions of the pool ....or the value of 'x' to calculate this

  without these ,   the answer I get is   

   area = 16x^2+8x

Mom is correct....   pick an example   say manuscript is 120 pages

60 pages at   10/day  = 6 days

60 pages at    30/day = 2 days

8 days total       120 pages/8days = 15 pages per day average

You can try it with other manuscript #'s too....results are the same.....

let 2x be the number of pages   then   x = 1/2 of the pages

2x pages   /  (x pages /10 pages/day   +  x pages / 30 pages/day)  = average

2/(1/10 + 1/30)  = 15 pages/day

40 x .01 x 1/2          +1          =   1.2     (just as gs85 found!)

Let the distance between the walls be  l

One rope goes from   y = 9 to 0   in length  l       now   let's also make l = 1 for convenience

  equation    y = -9/2x  +9  

other rope goes from 0 to 3   in lenght l (which is 1)

  equation   y = 3/2 x   

set them equal to find 'x'        3x = -9x+9         

                                               12x = 9

                                                 x = 3/4

now find the height by puttin 'x' into one of the equations      y = 3x = 3 * 3/4 = 9/4 meters high at cross

How about:

 2   3    7  11   13  17     

Multiply first equatin by   -3      then add to second equation to solve for z     as a start......

then   multiply first equation by -5      and add to third equation  to solve for   y

then use the values of   z   and  y   that you have found in any of the equations to solve for  x

From each of the non-colinear points to each poin on the line  would be   4 x 3 = 12 lines

from each of the 4 to the other three would   (4 x 3)/2 = 6 lines 

PLUS the colinear line

19 lines      (I believe)