Shop A: 55×45 = 2475 yuan. Buy 55 first, get 5 free, and ***60.

Store B: 60×45×0.8=2 160 yuan.

Store C: 60×45=2700

2700÷40=6 and 300.

6×40=240

2700-240=2460 yuan

It's cheaper to go to B shop.