Question

In sixteen states and the District of Columbia, the legal blood-alcohol level is 0.08. Use the formula A(x) = -0.0082x2 + 0.06x to compute blood-alcohol levels as a function of x (the time in hours). When is the first time that a person can be arrested for drunken driving after drinking 5 ounces of 80-proof whiskey in those states? (Hint: To find an answer through approximation, calculate the blood-alcohol level for every 0.2 hours beginning at x = 0.2.)

1.8 hours
2.2 hours
1.6 hours
3.0 hours

I don't understand the hint - it really made my confusion worse.