1/2 = 1/1*2 = 1/1 - 1/2
1/6 = 1/2*3 = 1/2 - 1/3
1/12 = 1/3*4 = 1/3 - 1/4
1/2+1/6+1/12+X+1/30 = 1-1/4 + x +1/30 = 1-1/30
x = 1/4 - 2/30 = 11/60
肯定是正的11/60谢谢了，那正确答案就你了不会错的，放心吧。