HELP ME PLZZZ ASAP! Tyler’s work is incorrect. Explain the error he made.

Tyler is simplifying the expression 6 − 2x + 5 + 4x. Here is his work:
6 − 2 + 5 + 4
(6−2) + (5+4)
4 + 9
13

M? aoc=96 ? space, m, angle, a, o, c, equals, 96, degree \qquad m \angle boc = 8x - 67^\circm? boc=8x? 67 ? space, m, angle, b, o, c, equals, 8, x, minus, 67, degree \qquad m \angle aob = 9x - 75^\circm? aob=9x? 75 ? space, m, angle, a, o, b, equals, 9, x, minus, 75, degree find m\angle bocm? bocm, angle, b, o, c: