.25(4) = 1 gallon
.25(8) = 2 gallons
.25(12) = 3 gallons
.25(16) = 4 gallons
.25(20) = 5 gallons
it would take 20 minutes to remove half the water (aka 5 gallons)
Than answer you looking for is I think B
I am assuming that the whole 3x - 6 in the fraction is the numerator
the this simplifies to 3x (3x - 6)
= 9x^2 - 18x (C)
13,800, sorry, i cant explain it well, but that the answer