Need some help on this.

Question

Lea and Brenda each improved their yards by planting grass sod and ornamental grass. They

bought their supplies from the same store. Lea spent $171 on 13 ft² of grass sod and 5 bunches

of ornamental grass. Brenda spent $90 on 5 ft² of grass sod and 10 bunches of ornamental grass.

What is the cost of one ft² of grass sod and the cost of one bunch of ornamental grass?

I need to know:

sq. foot of grass sod:

bunch of ornamental grass:

Answer 1

Call g grass sod and o ornamental grass.

13g + 5o = 171

5g + 10o = 90

Multiply the first equation by -2: -26g -10o = -342.

Add that result to the second equation:

5g + 10o = 90

-26g -10o = -342

-21g = - -252

g = -252/-21 = $12 for 1 sq foot of sod.

5(12) + 10o =90

60 + 10o = 90

10o = 30

o = 30/10 = $3 for 1 bunch of ornamental grass.

Answer 2

13S + 5G = 171

26S +10G = 342

5S + 10G = 90

21S =342-90= 252

S = 252/21 = $12 per grass sod

G = (90-5S)/10 = (90-5(12))/10 = $3 per ornamental grass