product means multiplication and a sum means addition, so the final form will look like this:
a(b+c)
a will be 2: 1+4+1+4 can be rewritten as (1+4)+(1+4)= we see that (1+4) is there twice: so that's where the 2 comes from.
and the b+c will be 1+4
so the result is 2(1+4)
factor 1: 2
factor 2: (1+4)