3
  x
 x
x    = 3

I havnt done algebra or any math in quite some time, so my memory is pretty faded. But since the exponents basically all have the same base (X) dont you just re-write the problem as x^3=3 and solve for x by taking the cubed root of 3, so get 1.4422[approx]??

Same would go for something like;

x^(x^(x^(x^7)))=7