Answer:
24 hours
Step-by-step explanation:
The computation of the number of hours taken by Bobby to build the robot by himself is shown below:
Given that
Bobby could take 12 hours
Together they could build in 8 hours
So based on the above information
the number of hours taken by Bobby to build the robot by himself is
Let us assume the above line be x
So,

x = 24 hours
Just divide -30 m/s (the change in velocity) by 12 seconds (the time required for the car to come to a stop):
-30 m/s
----------- = - 2,5 m / (sec)^2 (answer)
12 sec
12/16 which would reduce to 6/8 which can also reduce further to 3/4! :) so the final answer is 3/4.
The image isn’t working, just letting you know