This is a physics problem.
The law is that the momentum is preserved: total momentum before collsion = total momentum after collision
Momentum before collision = 80 kg.m/s - 100 kg.m/s = -20 kg.m/s
Then answer is b. - 20 kg.m/s
The fastest way is to just use a scientific calculator.
To do it without a calculator, use prime factorization.
I'll only do the second one which is the answer.
27 x 8
= 3^3 x 2^3 = 6^3
Which is a perfect cube.
its B because all the other ones don't make sense for the graph and you just do the slope and it is -3