Please Help:

I am trying to do a sumproduct between column B and C for the rows where the
values in column A are under 300 in the table below.
Is there a way to add this condition in the sumproduct formula or do it in
another way?

A B C
100 1,400 5
200 1,800 4
400 1,800 4
150 2,500 4
200 2,500 4
300 3,000 4

Really appreciate it.
Neda