Question

equality
if (ab = mr) and (mr = 18), then (ab=)

congruence
if (overline{ab}congoverline{mr}) and (overline{mr}congoverline{tw}) then (overline{ab}cong)

Explanation:

Step1: Substitute the value of MR

Given $AB = MR$ and $MR = 18$, we substitute $MR$ with 18 in the first - equation. So $AB=18$.

Step2: Use the transitive property of congruence

If $\overline{AB}\cong\overline{MR}$ and $\overline{MR}\cong\overline{TW}$, by the transitive property of congruence, $\overline{AB}\cong\overline{TW}$.

Answer:

18; $\overline{TW}$