Chapter 1 - Tools of Geometry - 1-3 Measuring Segments - Practice and Problem-Solving Exercises - Page 24: 17

They are congruent

To find the length of a segment on a number line, subtract the smaller point from the bigger point. Starting with MN, we see that $M=-3$ and N=3. Subtracting the smaller one from the bigger one gives: $3-(-3)=3+3=6$. For PQ, P=6 and Q=12. Subtracting the smaller one from the bigger one gives: $12-6=6$ These segments are congruent because they have an equal length.