Gabriella and stephanie each improved their yards by planting grass sod and ornamental grass. they bought their supplies from the same store. gabriella spent $172 on 14 ft2 of grass sod and 2 bunches of ornamental grass. stephanie spent $158 on 7 ft2 of grass sod and 9 bunches of ornamental grass. find the cost of one ft2 of grass sod and the cost of one bunch of ornamental grass.