Of the lines in the graph one has slope 1 one has slope 2 and one has slope 1/5 label each line with its slope

Consider this straight line.  The (x, y) coördinates at B have changed from the coördinates at A.  By the symbol Δx ("delta x") we mean the change in the x-coördinate.  That is,

Δx = x2 − x1.

what is the question? i am guessing you are looking for the area.

to find an area, you have to do length x width.

in this case, it would be 12 ft x 4 ft = 48 sq. ft