For the part A
2DE = BC
For the part B
2(2x+1) = 5x - 4
open the patrenthesis
4x + 2 = 5x - 4
collect the like term
5x - 4x = 2 + 4
x = 6
Length BC = 5x - 4 = 5(6) - 4 = 30 -4 = 26
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