How to find how long it will take a rocket to reach a maximum height

the rocket will reach its maximum height after 4 seconds.  

Step-by-step explanation:

The first term ( -4.9(t-4)^2 ) can never be positive, so the maximum height of 80 meters is achieved when t = 4.  

d (5 x (-20)) * (100 x (0.7))

step-by-step explanation:

5÷1/100 * -.7 *-20

copy dot flip

5*100 * -.7 *-20

rearrange

5*-20   * 100 *-.7

-100   *-70

7000

step-by-step explanation: