甲乙丙丁a,b,c,d 假设m=a+b+c+d a=1/2(b+c+d)=1/2m-1/2a b=1/3(a+c+d)=1/3m-1/3b c=1/4(a+b+d)=1/4m-1/4c d=60 a=m/3,b=m/4,c=5/m d=m-（a+b+c）=m-m(1/3+1/4+1/5)=60 m=3600/13 所以：甲乙丙丁的和为3600/13...