a b c d
1 .2 yes yes .3
2 .5 no no .5
3 .1 yes maybe 0

So, as in the above example, I need to put a formula in D1 so that it will
take the sum of column a if column b = c1. I hope this makes sense. And
keep in mind I will be continually adding rows to this and will need it to
cover the entire row, not just part of a row.

Thank you in advance and let me know if you need more clarification.