?
See work and answer below.
?
The diagonals are of the same length in a rectangle, so PR = SQ. Also, the diagonals bisect each other, so PT = TR and ST = TQ.
9x + 1 = 13x - 11 --> solve for x and you'll find SQ (also called QS). Afterward, halve this answer and you'll get TR. Give it a go.