3x/4-60*2/5=15 x=52
(1+2+3+...+2007)/2008
=(1+2007)*2007/2/2008
=1003.5
7/12-9/20+11/30-13/42+15/56-17/72
=7/12-17/72-(9/20-11/30)-(13/42-15/56)
=25/72-5/60-7/168
=25/72-1/12-1/24
=25/72-1/8
=16/72
=2/9
3x/4-60*2/5=15 x=52
(1+2+3+...+2007)/2008
=(1+2007)*2007/2/2008
=1003.5
7/12-9/20+11/30-13/42+15/56-17/72
=7/12-17/72-(9/20-11/30)-(13/42-15/56)
=25/72-5/60-7/168
=25/72-1/12-1/24
=25/72-1/8
=16/72
=2/9