Apainter will paint n walls with the same size and shape in a building using a specific brand of paint. the painter's fee can be calculated by the expression nklh, where n is the number of walls, k is a constant with units of dollars per square foot, l is the length of each wall in feet, and h is the height of each wall in feet.

if the customer asks the painter to use a more expensive brand of paint, which of the factros in the expression would change?