1a.) given the equation 5+ 6n-4n-15, explain how to get the answer n10.

In the figure below, segment ac is congruent to segment ab: triangle abc with a segment joining vertex a to point d on side bc. side ab is congruent to side ac which statement is used to prove that angle abd is congruent to angle acd? segment ad bisects angle cab. triangle acd is similar to triangle abd. segment ad is congruent to segment ac. angle cab is congruent to angle cba.

Cd is the perpendicular bisector of both xy and st, and cy=20. find xy.

How is this equation completed? i cannot find any examples in the book.