Let the cost of 1 pound of zucchini be 'z' and the cost of 1 pound of tomatoes be 't'. We can set up two equations using the given information:
9z + 6t = 21.15 (equation 1)
4z + 3t = 9.83 (equation 2)
We can solve for 'z' and 't' using the method of substitution:
From equation 2, we can express 4z as 9.83 - 3t:
4z = 9.83 - 3t
Substituting this expression for 4z in equation 1, we get:
9(9.83 - 3t)/4 + 6t = 21.15
Multiplying both sides by 4 to eliminate the fraction, we get:
9(9.83 - 3t) + 24t = 84.6
Expanding the left side, we get:
88.47 - 27t + 24t = 84.6
Combining like terms, we get:
-3t = -3.87
Dividing both sides by -3, we get:
t = 1.29
Substituting this value of 't' in equation 2, we get:
4z + 3(1.29) = 9.83
Simplifying, we get:
4z = 5.56
Dividing both sides by 4, we get:
z = 1.39
Therefore, 1 pound of zucchini costs $1.39 and 1 pound of tomatoes costs $1.29 at the farm stand.