c)7/13.5/19+7/19.8/13-3.7/19
=35/247+56/247-21/19
=7/19-21/19
=-14/19
d)12/11+7/15.9/22-(-8/15).9/22
=12/11+9/22.1
=3/2

c) 7/13 . 5/19 + 7/19 . 8/13 - 3.7/19
    = 7/19 . (5/13 + 8/13 - 3)
    = 7/19 . -2
    = -14/19
d)12/11 + 7/15 . 9/22 - -8/15 . 9/22
   =  9/22.(7/15-8/15) + 12/11
   = 9/22 . -1/15 + 12/11
   = -3/110 + 120/110
   = 117/110

c,7/13.5/19+7/19.8/13-3.7/19
=7/19.(5/13+8/13-3)=7/19.(1-3)
=-14/19
d,12/11+7/15.9/22-(-8)/15.9/22
=12/11+9/22.(7/15+8/15)
=12/11+9/22.1
=(24+9)/22
=33/22=3/2

 c
  = -14/19
d
   = 117/110