Problem 44775. Solve The Equation

There seem to be some problems. First, in the statement of the problem, I think the correct solution is z=3, not z=4. Second, in the test problems, the function solution() is called with an argument of x. It needs to be solution(x1,x2).

... also, in test #3, the solution is compared to y_correct rather than z_correct.

The problem description and test suite have been cleaned up.