13/17×5/6+17/13÷6
=13/17×5/6+17/13×1/6
=13/17×(5/6+1/6)
=17/13×1
=17/13
1.8×3/4+1.2×3/4-3/4
=(1.8+1.2-1)×3/4
=2×3/4
=3/2