甲x,乙y3x/5=(x+y)/3x/(x+y)=(1/3)/(3/5)=5/9甲占甲乙和的5/9
设甲X，乙Y3/5X=（X+Y）*1/34X=5YX=5/4Y甲占甲乙两数和的X/（X+Y）（5/4Y）/（5/4Y+Y）5/9
