A:A killer whale is longer than a sperm whale.
B:A sperm whale is shorter than a killer whale.
C:A sperm whale is longer than a killer whale.
根据历年气象统计资料,宜都三月份吹东风的概率为930,下雨的概率为1130,既吹东风又下雨的概率为830.则在吹东风的条件下下雨的概率为( )
某市为处理污水,需要铺设一条长为5000m的管道,为了尽量减少施工对交通所造成的影响,实际施工时每天比原计划多铺设20m,结果提前15天完成任务.设原计划每天铺设管道x m,则可得方程 ____.