Summing specific rows in a column based on a condition

I'm stuck on this specific problem and was hoping someone with more excel knowledge could shed some light on the issue.

What I want to do is a formula to check an entire column for a specific text (for purposes of a better explanation let's call this text "city" and the column range G:G), then if the text is found under any row in the G column I want it to sum the appropriate row in the column P:P.

So for example if the text is found under G3, G10 and G15 the formula would sum the numbers found under P3, P10 and P15.

So far I've tried things like =IF(G:G="city";sum=P:P) but I'm positive that I'm using a wrong approach towards solving this problem.

I've been trying to wrap my head around this for hours with no avail, any help would be appreciated =)