I tried making lgx = y, but I can't get it to work.
Next problem is:
I managed to get it down to
but I don't know what next. The end result should be 16.
And what about these two:
What I did, was
Then, and that's where I'm stuck. What I get is: I can't get a squared y out of it. And I don't know how to deal with the fraction.