<span>If Shelly rolls ball A in the positive x direction with a velocity of 7.5 meters/second, and It hits stationary ball B and they undergo elastic collision, thus the two balls have different masses, then the following statement which is true is the statement that stated that there was no y-momentum initially.</span>
Since force = mass X acceleration, then the force he excerts on the earth (aka his weight) equals his mass times the force of gravity.
Therefore
W = (66 kg) X (9.8 m/ss)
W = 646.8 kgm/ss
kg m/ss are also known as Newtons, so your answer is...
646.8 N