Let's use a system of equations to solve the problem.
Let x be the number of bags of mixed nuts and y be the number of bags of dried fruit that Mrs. Rivera bought. We know that she bought a total of 17 items, so:
x + y = 17 ... (equation 1)
We also know that the total cost of her purchase was $22.83, so:
1.49x + 0.99y = 22.83 ... (equation 2)
To solve for x and y, we can use equation 1 to solve for one variable in terms of the other. Solving for y, we get:
y = 17 - x
Substituting this expression for y into equation 2, we get:
1.49x + 0.99(17 - x) = 22.83
Simplifying and solving for x, we get:
1.49x + 16.83 - 0.99x = 22.83
0.50x = 6.00
x = 12
So Mrs. Rivera bought 12 bags of mixed nuts. Substituting this value into equation 1 to solve for y, we get:
12 + y = 17
y = 5
Therefore, Mrs. Rivera bought 12 bags of mixed nuts and 5 bags of dried fruit.