Question 760756
3 1/2 = 7/2
7 3/4 = 31/4
6 1/2 = 13/2
7/2 + 31/4 + 13/2
Common Denominator = 4

14 + 31 + 26
------------
     4

  =   71/4
=   17 3/4kg
Hope this helps.
:-)