13. Move 1 matchstick to make the equation true. Write the equation after moving the matchstick on the line:
$\qquad$ (Note: The " $Z$ " in the equation represents 2)
Answer: $3=11+1-2-7$
Exam Point: Matchstick Problem
Analysis: Prioritize the result remaining unchanged, only one matchstick can be moved, start from the right side of the equal sign, try to make the result of the equation 3. Therefore, we get $3=11+1-2-7$.