Answer:
14 units
Explanation:
The two halves of the diagonal are congruent, so ...
BE = DE
10x -3 = 8x -1
2x = 2 . . . . . . . add 3-8x
x = 1
BD = BE +DE = (10x -3) +(8x -1) = 18x -4
BD = 18·1 -4 = 14 . . . units
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It might be easier to figure DE = 8·1-1 = 7, then multiply by 2 to find BD = 14.