jeevanchand wrote:

Two water tanks x and y were drained simultaneously. If x contained 30 more gallons of water than y, and both tanks became empty at the same time, how long did it take the tanks to empty?

(1) For every gallon drained from tank y, 2 gallons drained from x

(2) Tank y was drained at a constant rate of 20 gallongs/hour.

X: y+30; (y+30)/R=t

Y: y; y/r=t

t=?

Stmt1: R=2r

(y+30)/2r=t

y/r=t

From the above, you will have tr=2tr-30

or tr=30

Insuff - we need r.

Stmt2; r=20 (gallon per hour)

Insuff.

Stmt 1&2:

tr=30

r=20

t=3/2 or 1.5 hours Suff

Hence, C.