1/4+1/28+1/70+1/130=?

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1/4+1/28+1/70+1/130=?
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1/4+1/28+1/70+1/130=?
1/4+1/28+1/70+1/130=?

1/4+1/28+1/70+1/130=?
1/4+1/28+1/70+1/130
=35/140+5/140+2/140+1/130
=(35+5+2)/140+130
=3/10+1/130
=3*13/130+1/130
=(39+1)/130
=40/130
=4/13

4/13

1/4+1/28+1/70+1/130
=1/4+[1/4-1/7+1/7-1/10+1/10-1/13]/3
=1/4+[1/4-1/13]/3
=1/4+3/52
=16/52
=4/13

1/4+1/28+1/70+1/130=(1/3)*[3/(1*4)+3/(4*7)+3/(7*10)+3/(10*13)]=(1/3)*[1-1/4+1/4-1/7+1/7-1/10+1/10-1/13]=(1/3)*(12/13) =4/13

1/4+1/28+1/70+1/130
=7/28+1/28+1/70+1/130
=8/28+1/70+1/130
=2/7+1/70+1/130
=20/70+1/70+1/130
=21/70+1/130
=3/10+1/130
=39/130+1/130
=40/130
=4/13