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PT33 Section 4 Game 2

There is a grouping game about birds in a forest. G, H, J, M, S, W

One rule states If J, M, or both are in the forest, then so are H
Should I diagram all three possibilities?
J -> H
M -> H
J and M -> H

When I take the contrapositive and deduce all rules I get the first chain:
Not S -> J -> H -> Not G -> - Not W
Then when I flip that around I get a second chain:
W -> G -> Not H -> Not J AND Not M -> S
Since J or M or both -> H does the contrapositive of the first chain mean that Not J AND Not M or is it Not J or Not M

for the first part, there's no reason to write down J and M --> H. it's encompassed by the first two rules. as a result, it's just wasting time.

since the contrapositive of those two rules are

J -->H / H --> J
M-->H / H --> M,

then H means BOTH J and M on the second chain.

If the rule was simply 'J and M' --> H', then it would be true that H --> J, M, or both.

because both conditions are sufficient by themselves to bring about H, you've got to knock both of them out, which supersedes the other rule.