9514 1404 393
Answer:
x = 6
Step-by-step explanation:
The angle bisector divides the sides proportionally.
(6x -1)/42 = (10x +5)/78
13(6x -1) = 7(10x +5) . . . . . . . multiply by 546 = LCM(42, 78)
78x -13 = 70x +35 . . . . . . . . eliminate parentheses
8x = 48 . . . . . . . . . . . . . . . . add 13-70x
x = 6 . . . . . . . . . . . . . . . . . divide by 8
