Berapa hasil pencahan cara menemukan jawabannya

A. 1 1/3 + 2 2/5 + 11/2
= 4/3 + 12/5 + 11/2
= (20×4) / 60 + (12×12)/60 + (11×30)/60
= 80/60 + 144/60 + 330/60
=554/30
=18 14/30
=18 7/15

b. 7 3/4 – 2 1/12 – 2 1/3
= 31/4 – 25/12 – 7/3
= 93/12 – 25/12 – 28/12
=40/12
=3 4/12
=3 1/3