Otto put 12 4/9 pounds of electrical supplies into crates each crate held 1 7/9 pounds of supplies. how many crates did otto use

For this, you would need to divide the total ppinds by how many pound each box can hold to find the total number of boxes.
Covert the mixed fractions in improper fractions.
12 4/9 = 112/9
1 7/9 = 16/9
Now divide them. Remeber that dividing by a fraction is the same as multiplying by its reciprocal. So this woumd be your expression to solve:
112/9 × 9/16 > The 9s cancel with cross simplifying.

112/16 = 7
This means Otto will use 7 boxes!
I hope this helps :D