4分之1加28分之1加70分之1加130分之1加208分之1
=7/28+1/28+1/70+1/130+1/208
=8/28+1/70+1/130+1/208
=2/7+1/70+1/130+1/208
=20/70+1/70+1/130+1/208
=21/70+1/130+1/208
=3/10+1/130+1/208
=39/130+1/130+1/208
=40/130+1/208
=4/13+1/208
=64/208+1/208
=65/208