Simplify equation (all are vectors):

(XY - YZ) - (ZT + XT) + (ZY - ZT)

The given answer is 3TY, but I don't know how to get that answer. Please help. For example I'd say that XY - YZ = -YX - YZ = ZX, but that's not TY... Then I'd say ZT - XT = -ZT + XT = ZX(also not TY), then ZY - ZT = TY. So that would be ZX - ZX + TY = TY (not 3TY)