A company has two plants $A$ and $B$ to manufacture motorcycles. $60%$ are made at $A$ and $40%$ at $B$. Of these, $80%$ of $A$’s and $90%$ of $B$’s motorcycles are of standard quality. A randomly picked motorcycle from the total production is found to be of standard quality. If $p$ is the probability that it was manufactured at plant $B$, then $126p$ equals: