Math Practice Problem Generator — illustrative example

INPUT
Generate one practice problem for adding fractions with a common denominator.

RESULT
Problem: 2/7 + 3/7. Answer: 5/7, because two seventh-sized parts plus three seventh-sized parts make five seventh-sized parts.

REVIEW
Practice questions should vary the relevant skill while keeping answers checkable. Include enough explanation to diagnose a wrong answer.

This is a teaching example, not a live execution record.