2. Let the distance be S, the speed of vehicle A be V, V=S/3.5, (S/2-V)*3.5+35=S, then S =140;

3. Let the number of winners of the first prize be A, then a+4a+8a=26, then A = 2；;

There were 40 girls and 60 boys. Later, the total number of girls was *** 120 (accounting for two thirds of 60+ 120 = 180), so 80 new girls were selected (= 120-40).