(c) Only the positive solution makes sense because you cannot have a negative side length. (d) Since one side of the painting is 20 inches, all four sides together will be 20*4 = 80 inches
No, they are not equivalent. The numerators are equals, but the denominators are not, they are not equivalent. If the first one would be 6/8, they would be equivalent, because we can simplify the fractions by 2 and we got 3/4 again. Good luck !