Linear interpolation to find the median confusion - two methods, two different answers

Question

I am given the following in a worked example (see picture).

That is the method used to find the median by interpolation.

However, they say the fractions $\frac{a}{b}$ and $\frac{c}{d}$ are equivalent. I thus tried to use $$\frac{b-a}{b} = \frac{d-c}{d}$$ to find the median, but this gave a different answer:

$$\frac{36.5-m}{3} = \frac{22}{20}\Rightarrow m = 33.2$$

Where am I going wrong ? What is the issue?

Answer 1

$d = 57 -27 =30\ne 20$

$\frac {36.5 - m}3 = \frac {22}{30}$

$36.5 - m = 2.2$

$m = 34.3$.