Answer: the answer is alternate interior
1st number can be 0-9 = 10 numbers
2nd number can be 0-9 = 10 numbers
3rd number can be 0-9 = 10 numbers
10 * 10 * 10 = 1000 combinations
Pipe B is faster. I can't answer the second part. Pipe A pumps 15.16 liters btw