From the information given, triangle BNV is similar to triangle BRG. This means that the ratios of their corresponding sides are equal. Thus,
BN/BR = BV/BG
BN = 12
BR = 4x + 7
BV = 8
BG = 18
Thus,
12/(4x + 7) = 8/18
By crossmultiplying, we have
8(4x + 7) = 12 * 18
By expanding the parentheses on the left, we have
32x + 56 = 216
32x = 216 - 56 = 160
x = 160/32
x = 5
