Three machines, known as M1, M2, and M3, contribute to the production of a batch of items. M1 and M2 are responsible for 35% and 25% of the production respectively. There is a 2% defect rate for the items produced by M1, 1.2% defect rate for M2, and a x% defect rate for M3's items. The entire batch of items has a defect rate of y%, where both x and y are integers. (y<8). The task is to determine the total number of possible pairs of x and y.