Distance to star using color index
There is a relationship between $E(B-V)$ and the reddening in any other colour. The exact value depends on the type of dust, the extinction value itself and the intrinsic spectrum of the star (as does the 3.0 coefficient mentioned in your question).

However, for the purposes of estimation, the canonical relationship is $E(U-B) = 0.72 E(B-V)$ (e.g. Pandey et al. 2003).

Thus you can calculate $E(U-B)$, then $E(B-V)$, then $A_V$, then $V_0$ and use this with $M_V$ to get the distance.