第1个回答 2009-12-22
5x-2(20-x)=51
x=13
第2个回答 2010-01-01
5X x 20 -2X x 20=51
自己解··········································································································································就好了
第3个回答 2009-12-24
设打中x枪,没打中y枪
x+y=20
5x-2y=51
解得x=13,y=7
打中13枪
第4个回答 2009-12-22
设打中x枪,没打中y枪
x+y=20
5x-2y=51
解得x=13,y=7
打中13枪
或:
设打中x枪,没打中20-x
5x-2(20-x)=51
解得x=13
打中13枪本回答被提问者采纳