Are f(x) = 3x - 10 and 2x + 7y = 28 both functions, if not which one isn't and why?

Afurniture manufacturer produces chairs and sofas. each chair requires 10 yards of fabric, and each sofa requires 20 yards of fabric. the manufacturer has 300 yards of fabric available. to fulfill orders, the number of sofas must be at least twice the number of chairs. let x be the number of chairs and y the number of sofas. which inequalities are described in the problem? check all of the boxes that apply

Find the area of the surface obtained by rotating the curve z=4e^2y from y = 0 to y =1 about the y-axis. the area is square units

Given -9,6 is on the graph of f(x) find the corresponding points for the function -1/2f(x)