There are a total of 20 single-page spreads * 2 = <<20*2=40>>40 double-page spreads.
As these are made up of 2 pages each, there are 40 double-page spreads * 2 pages = <<40*2=80>>80 pages in the double-page spreads.
In total, there are 20 single-pages + 80 double-pages = <<20+80=100>>100 pages in the spreads.
A block of ads is printed every 4 pages, so there will be 100 pages / 4 pages/block = <<100/4=25>>25 blocks of ads.
This is a total of 25 blocks * 4 ads = <<25*4=100>>100 ads.
As each ad takes up a quarter of a page, this must create an additional 100 ads * 0.25 = <<100*0.25=25>>25 pages.
Therefore, the press has printed 100 pages from the spreads + 25 pages of ads = <<100+25=125>>125 pages.
Since brochures are made up of 5 pages each, this creates a total of 125 pages / 5 = <<125/5=25>>25 brochures.
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