Grammar First Set

E' -> E $
E -> T N
N -> + T N | - T N |
T -> F M
M -> * F M | / F M |
F -> id | ( E )

Using the following grammar I have to compute the First(*FM).
I did sth like this but I think It is wrong:/
First(*FM) = First(*) U FIrst(F) U (First(M) - { })
= {*} U {id, ( } U ({*,/, } - { })
= {*, id, ( , / }


I read a lot of examples about it but I cannot understand this
subject:/ Could you tell me what I did wrong?
Please help me.

Sorry if it is a quastion not to this group

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