It appears as if 12cm is half the length of the side so we can assume that the total length of one side is 24cm.
The area of a square is given by the equation 
where s is the length of the side.
A=576
The area of this square is 576cm2.
Hope this helps!
The answer will be/is 0,1
-x^2 - 2x - 5=0
-(x^2 + 2x + 1) -4=0
(x +1)^2= -4
=> Impossible. There is no x
New pump:
5 hours = 1 pool
1 hour = 1/5 pool
Old pump:
15h = 1 pool
1h = 1/15 pool
If both work together
1h = 1/5 + 1/15 = 4/15 pool
4/15 pool = 1 hour
1/15 pool = 1/4 hour
15/15 pool = 1/4 x 15
1 pool = 3.75 hours or 3 hours 45 mins
