Hi Probolobo,
I worked it out but not with simultaneous equations.
I do not think I used any simultaneous equations, not that I remember.
It was more a matter of working out which numbers a letter could NOT be.
Most were worked out by elimination.
There were about 5 possible sets of 10 at the end. I eliminated the wrong sets via substitution.
But then this is not much different from how I did the rest. It was almost all done by logical elimination.