(2) Let A buy X clothes and B buy Y clothes, and get the following relationship:
① X+y=60
② 60X+90y=4200
We can get 3x = 60-y from ①, and if we substitute ③ into ②, we can get the following results: Y = 20 (the number of clothes in B), then X = 40 (the number of clothes in A).
(3) Let A buy X clothes and B buy Y clothes, and the total profit is Z, then the following relationship is obtained:
① y=70
② 2X+2=y
③ 20X+30y=Z
Solution: X=34 y=70 Z=2780.