A plastering contractor charges $18 per square yard (that is $2 per square foot). what is the cost of plastering 100 feet of wall in a house with an 8 foot ceiling

Basically, this problem is going to require you to solve for the area and multiply it with the given cost unit.

Area = Length*Height

Area = 100 ft * 8 ft = 800 ft²

Total Cost = (Unit Cost) (Area)

Total Cost = ($2/ft²) (800 ft²)

Total Cost = $1,600