There are two and five in the zoo.
A:sheep; deer
B:sheep; giraffe
C: bears; deers
D:sheeps; tigers
某课外活动小组的学生准备分组外出活动,若每组7人,则余下3人;若每组8人,则少5人.求课外活动小组的人数x和应分成的组数y,依题意得方程组为( )