You can simply enter the two equations into Desmos in the future unless showing your work is required
Solution is (2,3)
It looks like it is 5/3 for line E and 2/1 for line D.
1.49/6 = 0.248 rounds to 25 cents per oz
3.59 / 13 = 0.276 rounds to 28 cents per oz
choice A is the lowest rate