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 .
3(x-6)(x+2)
hope this helps
620*1.35=837 so 837ml is the answer
It would be x=-4 have a good day