Paint Express charges $30 per gallon of paint plus $1.10 per square foot of wall space. Color Creations charges $24 per gallon of paint plus $1.20 per square foot of wall space. Robert estimates he will need four gallons of paint for the rooms he’d like painted. How much wall space would make Paint Express less expensive than Color Creations?
when using 4 gallons of paint, we want to find when
30*4 + 1.10x < 24*4 + 1.20x
x > 240
so, if there are more than 240 square feet, Paint Express is cheaper.