Min 6年以上以前 T(4/5) =(4/10)(520-3/5(T)) T(4/5)(10/4)=520-3/5T 2T =520-3/5T 2T+3/5T =520 10T/5+3T/5 =520 13T/5 =520 T =520•5/13 T =40•5 T =200 留言