17-2/7-16/7
=17-2/7-(2/7+14/7)
=17-2/7-2/7-14/7
=(17-14/7)-(2/7+2/7)
=15-4/7
=14又3/7
=101/7
或者
17-2/7-16/7
=17-(2/7+16/7)
=119/7-18/7
=101/7