Answer:
Sam's and Abigail speeds before colliding were a. 12.34 m/s and b. 2.86 m/s, respectively. Their total kinetic energy was diminished by c. 1484.42 J, approximately
Explanation:
By conservation of momentum, we have

Writing for each direction at a time,

Their kinetic energy changed by

KE= 1/2MV^2 - equation
KE= 1/2 (2 kg)(15 m/s)^2 - plug it to the equation
KE= (1 kg)(225 m/s) - multiply
KE= 225 J - Answer (letter D)
Hope this helps