a , 1/ 2+ 1 /3 + 1 / 4 + 1/ 6
=5/6+1/4+1/6
=1+1/4
=5/4
b, 53 / 4 . 11/ 16 - 23/4 . 11/16
=11/16(53/4+23/4)
=11/6.19
=209/6
53 / 4 . 11/ 16 - 23/4 . 11/16
=11/6,19
=209/6
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