how to generate report based on adding costs of particular category

I have a check register with the date, category, inflow, outflow, etc. and would like to generate a report adding up all the (for example) outflows made on gas.

I have tried a bunch of different formulas (I am just a rookie) such as VLOOKUP, SUMPRODUCT, etc. but don't really know how to come up with what I am looking for.

Thanks for your help.