Question

小明和小丁进行数学竞赛,做对一题得10分,做错一题扣3分,两人各做了10道题,两人共得109分,小丁比.

Answer 1

设小明做对了 x 题,小丁做对了 y 题

10 x -3(10-x) + 10y -3(10-y) =109

10 x -3(10-x) -[ 10y -3(10-y)] =13

x = 7 ----小明做对

y= 6 ---- 小丁做对