Answer:
AC = 24
Explanation:
DE is the midline of the triangle, parallel to AC. It is half the length of AC, so ...
2·DE = AC
2(2x -14) = 3x -15
4x -28 = 3x -15 . . . . . eliminate parentheses
x = 13 . . . . . . . . . . . . . add 28-3x to both sides
AC = 3x -15 = 3(13) -15
AC = 24
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Additional comment
DE = 2(13) -14 = 12, half the length of AC.