I'm trying to add the values in a column if the row includes two different
criteria:

2800650 1 30200028
2800650 1 30200028
2800650 1 30200028
2800750 1 30200028


if the value in column a="2800650", and the value in colum c="30200028" then
count b1:b4
(in this case would = 3)