Two wooden crates rest on top of one another. The smaller top crate has a mass of m1 = 20 kg and the larger bottom crate has a mass of m2 = 86 kg. There is NO friction between the crate and the floor, but the coefficient of kinetic friction between the two crates is μk = 0.68. A massless rope is attached to the lower crate to pull it horizontally to the right (which should be considered the positive direction for this problem).
1)The rope is pulled with a tension T = 371 N (which is small enough that the top crate will not slide). What is the acceleration of the top crate?

So you are saying you actually have a mass of 106 kg riding on a frictionless surface, right so far? "to the right (which should be considered the positive direction for this problem)." How/why does this matter? A mass riding on a frictionless level surface will travel only in the direction of the force. Can you explain further? Is this a actual question, word for word, from a text or worksheet?