Given the triangle ACE
BD // CE
So, the segments between the parallel lines will be proportional
AB = 4
BC = 6
AD = x+3
DE = 2x+1
so,

So, the value of x = 7
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Given if CE = 30
We need to find the length of BD
So, using the similarity between the triangles ABD and ACE
So, the corresponding sides will be proportionals
So,

AB = 4
AC = 4+6 = 10
CE = 30
So,

So, the length of BD = 12