The Intersecting Secant Theorem says
EC × ED = EB × EA
(x+4)(x+4+1) = (x+1)(x+1+11)
(x+4)(x+5)=(x+1)(x+12)
x^2 + 9x + 20 = x^2 + 13 x + 12
8 = 4x
x = 2
Check:
6(7)=42
3(14)=42, good
Answer: 2
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