解:根据题意,长方体槐棚的侧面积为:S侧=2×长×高+2×宽×高 =2×20×25+2×12×25 =1000+600 =1600(铅敬则cm²)答:略。稿兆
2(20+12)x25=1600
2*(20+12)*25=1600平方厘米
[(20*25)+(25*12)]*2