Question 211575
4X/(4+X)=(X-2)
4X=(4+X)(X-2)
4X=4X+X^2-2X-8
4X-4X=X^2-2X-8
X^2-2X-8=0
(X-4)(X+2)=0
X-4=0
X=4 HOURS FOR THE SECOND PIPE TO FILL THE TANK WORKING ALONE.
PROOF:
4*4/(4+4)=4-2
16/8=2
2=2