Neither of them are correct. When you plug in both of the fractions into the equation, you get answers like 2/9 (from plugging in 1/3) and 1/9 (from plugging in 1/6). None of them are equal to 9.
You plug in 2x + 4 into the y for the other equation (3x +y ) and solve for it
C = 2 pi r
but c = 15
15 = 2 pi r
15 = 2 * (22/7) * r
r = (15*7) / 2 / 22
r = 2.386
The correct answer should 1.1333
Michelle will earn $15 from the interest rate.