You are jumping on a trampoline. For one jump, your height y (in feet) above trampoline after t seconds can be represented by y=-16^2+24t. How many seconds are you in the air? I need an explanation/work for it!!!

10 points and picture added if there is any confusion in problem

The figure shows triangle def and line segment bc, which is parallel to ef: triangle def has a point b on side de and point c on side df. the line bc is parallel to the line ef. part a: is triangle def similar to triangle dbc? explain using what you know about triangle similarity. part b: which line segment on triangle dbc corresponds to line segment ef? explain your answer. part c: which angle on triangle dbc corresponds to angle f? explain your answer. asap