It's B, because of the definition of a function.
Step-by-step explanation:
7a - 4b = 2b - 5a
7a + 5a = 2b + 4b
12a = 6b
a = 6b/12
a = b/2
The tangents are equal length, so
.. 8x = x^2
We presume their length is not zero, so we can divide by x to get
.. 8 = 2x
.. 4 = x
Then the length of each tangent is 8*4 = 32 units.
