3 per 9 - 32 per 80 = jawab

3/9 - 32/80
= 240/720 - 288/720
= - 48/720
= - 1/15

Atau
32/80 disederhanakan
=32/80÷8=4/10
4/10÷2=2/5
=3/9-2/5=15-18/45
= -3/45 Disederhanakan
= -3/45÷3= -1/15