using synthesis theory, you choose a passband insertion loss ripple, and bandwidth, and the values for the quarterwave transmission lines and the resistors pops out.
there should be a ton of papers on it, or even some apps to calculate them.
the point is, there are a large set of values for the resistors, and until you choose the boundary conditions, you can not calculate them
btw, those big blobs of solder are NOT your friend!