for this, we have to look at ratios between the prices.
so, for A, its $350 for 100 copies
if we take 350/100, you get that one copy is $3.50
using this info, we can solve for 40 papers. 40*3.5 is 140, so it would actually cost 140 dollars for 40 papers
now B.
150/40 is $3.75, so one copy is 3.75
so 100 copies. that would be 3.75*100 which is 375 for 100 copies