### Problem Summary The calculation is attempting to add an integer value to a string value. ### Diagnosis The failure occurs because one of the values used in the total calculation is represented as text rather than as a numeric value. ### Root Cause The likely root cause is a type mismatch: the value being added to the numeric total has not been converted to an appropriate numeric type before the calculation. ### Evidence The error explicitly reports an unsupported int + str operation. This confirms that the two operands have incompatible types for the + operation. ### Fix Strategy Convert the input to the appropriate numeric type at the point where the value enters the calculation, while preserving the existing calculation logic. ### Corrected Code The smallest likely fix is: total = price + int(quantity) If the input may contain decimal values, use an appropriate numeric conversion such as float() based on the actual data format. ### Verification Tests 1. Test with a valid integer quantity. 2. Test with a numeric string such as "3". 3. Test with an invalid value such as "abc". 4. Confirm that the resulting total is correct. ### Regression Check Verify that existing calculations using already-numeric values continue to work correctly. ### Final Debugging Checklist - Confirm the input type. - Convert the value before arithmetic. - Handle invalid input. - Retest the original failing case. - Test related valid and invalid inputs.