помогите решить 2 примера в дробях [13/18-3/8]-[5/8-1/3] [19/24-4/15]-[7/6-6/15]

[13/18-3/8]-[5/8-1/3]=[52/72-27/72]-[15/24-8/24]=25/72-7/24=25/72-21/72=
=4/72=1/18

[19/24-4/15]-[7/6-6/15]=[95/120-32/120]-[35/30-12/30]=63/120-23/30=
  =63/120-92/120=-29/120