it is given in the question that
Alpha printing will make 400 brochures for $100. Omega printing will make 1,000 brochures for $100.
For Alpha, cost of 1 brochure is

For Omega,
Cost of 1 brochure is

So choosing Omega printing, you will save

on each brochure .
I’m not sure i understand what your trying to say
30 should be the correct answer
You have to turn the number or ratio and simplified the number and put it in to the chart like the norm number
.