If \dfrac{a}{b}=2 b a =2start fraction, a, divided by, b, end fraction, equals, 2, what is the value of \dfrac{4b}{a} a 4b start fraction, 4, b, divided by, a, end fraction ?

So, we have two equations. The first one is a/b = 2, and the other one is to find the value of 4b/a. In order to solve this, let's find the value of b/a. As you can observe, b/a is the reciprocal of a/b. Therefore, b/a is also the reciprocal of 2. This means that b/a = 1/2. Now, substituting this to the second equation, the answer would be

4b/a = 4(1/2) = 2

The answer is 2.