Any question answered...

excel question:

I need a cell to show:

X = 5% of y where a is greater than zero. (a forms part of the calculation for y).

...so in my head it needs to be something like:

=sumif(b1*0.05,a1>0)

[assuming a1 = a and b1 = y]

...but it doesn't work. Any advice, or other search terms i should be using? I feel like i'm so close.

=if(a1>0,b1*0.05,0)