Answer:
2 or 12
Explanation:
The answer that we will use this equation 1/t1 +1/t2=1/ttotal
where t1 is the time of smaller pipe while t2 is the of the larger pipe
Given t total =4 while t2 is equal to t2=t1-6
So know you can solve the problem by changing it into (2t1-6)/(t1*(t1-6))=1/4
8( t1-3)=(t1^2-6t1)
t1^2-14t1+24=0
t1=2 or 12