Matching a primal and its stated dual — an unresolvable coefficient clash

The two LPPs P and Q are duals of each other, where P: Max $ax+2y$ s.t. $2x+y\le3, bx+2y\le c, x,y\ge0$, and Q: Min $3u+4v$ s.t. $2u+4v\ge2, u+2v\ge5, u,v\ge0$. Then, $(a,b,c)$ is equal to: