is the matrix I'm trying to solve with the following unknowns.

so I've put them into 6 simultaneous equations... which I think makes this therefore solvable.

e+t+v+w=150

d+e+g+v=300

d+e+f+w=240

f+t+u+w=160

g+t+u+v=210

d+f+g+u=250

my calculator can do 6 unknowns... and I've only ever been able to do 2 unknowns algebraically, can anyone help please?