Answer:
12
Step-by-step explanation:
A stuntman jumping off a 20-m-high building is modeled by the equation h = 20 – 5t2, where t is the time in seconds. A high-speed camera is ready to film him between 15 m and 10 m above the ground. For which interval of time should the camera film him?
Answer:

Step-by-step explanation:
Given:
A stuntman jumping off a 20-m-high building is modeled by the equation
-----------(1)
A high-speed camera is ready to making film between 15 m and 10 m above the ground
when the stuntman is 15m above the ground.
height
Put height value in equation 1





We know that the time is always positive, therefore 
when the stuntman is 10m above the ground.
height
Put height value in equation 1







Therefore ,time interval of camera film him is 
I got 7.64 because you round the 3 to 4 since the 7, in the 3rd decimal place is higher than 5
The answer to this problem is 23.5 . You are going to start by multiplying whats inside the paranthesis’s and then you’re going to calulate the sum and then difference and you should be left with 23.5