I think the answer is a but I'm not sure
When the ball hits the ground, the height is 0.
0 = 100 - 16t²
0 = (10 - 4t)(10 + 4t)
0 = 10 - 4t or 0 = 10 + 4t
4t = 10 or -4t = 10
t =
or t = 
Time cannot be negative (unless you have a time machine) so disregard 
Answer: t =
= 2.5 seconds
Answer:
7
Step-by-step explanation:
you need to use PEMDAS
3 x 3 x 3 = 27 divided by 9 is 3 and 10-3=7
For this translation, you need to replace every occurrence of "x" with "x-3", and every occurrence of "y" with "y+5".