(7/12*7/24+2/3)*3/7
=7/12x7/24x3/7+2/3x3/7
=7/12x1/8+2/7
=7/96+2/7
=241/684
如果本题有什么不明白可以追问,我题目写错了是(12/7*7/24+2/3)*7/3(12/7*7/24+2/3)*7/3=（1/2+2/3）x7/3=7/6x7/3=49/18