MathNet 2018-part-02 — 181 problems (EN–VI) Question 104

Let $M$ be the intersection of the diagonals of a cyclic quadrilateral $ABCD$. Find the length of $AD$, if it is known that $AB = 2$ mm, $BC = 5$ mm, $AM = 4$ mm, and $\frac{CD}{CM} = 0.6$.