Filling and wrapping inv 3

Inv 3.1:
inv 31 wu
inv 31 wu part 2

Inv 3.2:
fw inv 32 wu recipe scale and finding a linear equation from text

Summary:
fw inv 32 d1
fw inv 32 d 2
fw inv 32 sum

Note: To study for the Benchmark 3, you should review the warm-up vodeos from the past couple of weeks.