Answer:
7,79 seconds
Step-by-step explanation:

You need to use the acceleration formula. A is acceliration,
is change in velocity and t is time.
You need to multiply the formula with t and divide by a and you get
a*t=

t=
/a
after that you just need to insert the numbers
change in velocity is 76.4 minus 0.
acceliration is gravitational acceleration which is 9.81.
After that you get
t=76.4/9.81
t= 7,787971458 s