7 9/10 - 1 1/4 - 3 2/5

sorry kalo salah........

=7 9/10 - 1 1/4 - 3 2/5
=(7 × 10 + 9)/10 - (1 × 4 +1)/4 - ( 3 ×5 +2)/5
=79/10 - 5/4 - 17/5
= 158/20 - 25/20 - 68/20
=133/20 - 68/20
= 65/20
= 3 5/20 = 3 1/4