The diagram above represents the layout of a new prison.
There are 21 guards, 45 prisoners, 6 towers for the guards, and 5 compounds for the prisoners.
The towers are numbered 1 to 6 and the compounds are lettered A to E.
All of the compounds are triangular in shape and have a guard tower at each of the three corners.
The number of prisoners in a compound is equal to the total number of guards in the towers on the corners of the compound.
There are 11 prisoners in compound A, 1 guard in tower number two, and 3 guards in tower number six.
No two towers or compounds contain the same number of guards or prisoners.
How many guards are there in each of the six towers?