I just don't get these type of problems at all. Please help if at all possible the problem is as follows:
An astronaut on the moon tosses a ball upwards; when will the ball initially be 35 feet above the lunar surface if the ball's height(feet) follows:
-2.6t^2 + 32.1t + 5.5 and t is in seconds from release?
All you need to do here is set and solve for t [this is a quadratic that can be easily solved using the quadratic equation].
Note that you'll get two values both of which should be positive. The smaller value of t tells you the time it takes to initially reach the height of 35 feet (before reaching the maximum height). The second t value tells you when it reaches a height of 35 after it has reached its maximum height and starts to fall back to the surface.
If you still have questions, feel free to ask.