There is always C52= 10, and two outstanding students are selected to participate in the math competition. Suppose there are three people after removing two people. If you choose two people from these three people, there are C32=3 situations, which do not include Party A and Party B. After excluding these three situations, one of Party A and Party B must participate in the remaining seven situations, and then both parties must participate. Therefore, the probability that at least one of Party A and Party B will participate in the competition is (10-3)/ 10=0.7.