Reciprocal means the inverse of the fraction. For your mixed number 7 and 1/3, turn it into fraction by multiplying 7 with the denominator which is 3, then add the numerator which is 1 to get the numerator of a normal fraction which is 22. The numerator remains the same.
The fraction is 22/3. As mentioned above, reciprocal means the inverse, so the final answer is 3/22