Surface Area and Volume · Hard problem

A moving company wraps furniture crates in protective film before shipping. Each crate is a rectangular prism $3$ m by $2$ m by $1\frac{1}{2}$ m, and there are $2$ identical crates to wrap completely (all $6$ faces of each). Protective film comes in rolls that cover $20$ square meters each. What is the fewest number of rolls needed to wrap both crates?