Given the following array:

1024 20
100 30
600 20
700 10
800 10

Is there a COUNTIF equivalent to the following formula?
=SUMPRODUCT(--(A4:A8200),--(A4:A8/B4:B8=30))

I am just starting to appreciate the power of SUMPRODUCT, so I want to try
and understand limitations of it as well as replacement functions.