Answer:
4 seconds
Step-by-step explanation:
Given
Ann has an empty cup and add 1 ounce of water per second
let the number of seconds required to fill the cup be x
let the total be y
in x seconds Ann will have x ounces of water in the cup.
so the total amount of water in Ann's cup will be
Bob has 12 ounces of water and drinks 2 ounces per second
also, let the number of seconds required to empty the cup be x
let the total be y
Step two:
equate the two equations above and solve for x
collect like terms
divide both sides by 3
Therefore, after about 4 seconds Ann and Bob's cup will have the same amount of water