Brain Teaser

Answer: 35

Let L1 be the amount of water Dr. Johnson can drink from the container in one day, and L2 be the amount of water that his wife can drink in one day. . Let A be the amount of water in the container. Hence, we have that A= 14xL1, and A=10x(L1+L2). Therefore, 14L1 = 10L1 + 10L2, or 4L1 = 10L2. Therefore, L1/L2 = 10/4 = 2.5
Let N be the number of days it would take the wife to finish all the water from the container. Then, A=NxL2, so 14xL1 = NxL2. Therefore, N = 14xL1/L2 = 14×2.5=35