Excel: Count Values In One Column On Basis Of Other Column Value

Attachment 226640

COLUMN A
5
5
6
9
COLUMN B
A
A
B
B

A=10
B=15


Hi there, I need help creating a formula that adds Column A, only if Column B = 'A'.
I then need to multiply that counted value by another cell.

Can someone please help me? I think I'm over-thinking this.

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