31×多少-(200+多少)=400 31x-200-x=400 =>31x-x=600 =>30x=600 =>x=20 运算步骤怎么算

问题描述:

31×多少-(200+多少)=400 31x-200-x=400 =>31x-x=600 =>30x=600 =>x=20 运算步骤怎么算

31*x-(200+x)=400;-->31*x-200-x = 400; (31-1)*x = 400+200; 30*x = 600; x=20