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Short Answer D
Formula
Measured from the intersect point of the two secants (AC and AD) the relationship is 
AC * AB = AE * AD

The formula holds true for any two secants.

Givens
AC = 2 + 1.5 = 3.5
AB = 2
AE = 2.5
AD = 2.5 + x

Sub and Solve
3.5 * 2 = 2.5*(2.5 + x)      Remove the brackets on the right.
7 = 6.25 + 2.5x                 Subtract 6.25 from both sides.
7 - 6.25 = 2.5x 
0.75 = 2.5 x                      Divide by 2.5
0.75/2.5 = x
x = 0.3     <<<<<<<<<<<Answer

B. because the 7 represents "seven times", x represents "a number", 12 represents "plus twelve", and -4 represents "minus four"