Hello!
CD^2 = CB * CA
Put in the values we know
25^2 = 14(14 + x)
Distribute the 14
25^2 = 14^2 + 14x
Subtract both sides by 14^2
25^2 - 14^2 = 14x
Square the numbers
625 - 196 = 14x
429 = 14x
Divide both sides by 14
x = 30.6
The answer is D)30.6
Hope this helps!