You were on the right track with the amount of work you did but you just need to finish it. Starting with the following:
x/(2x-1) = Log(0.250/log(6)
Now evaluate and divide the logarithms on the right side and you should get:
x/(2x-1) = -0.7737056145 *I write down the entire value shown on the calculator*
Now multiply both sides by (2x-1) and you should get:
x = -0.7737056145(2x-1)
Using the Distributive Property on the right side you should get:
x = -1.547411229x + 0.7737056145
Now add +1.547411229x to both sides and you should get:
x + 1.547411229x = -0.7737056145
Now add 1x to 1.547411229 on the left side of the equation to get:
2.547411229x = -0.7737056145
Now divide both sides by 2.547411229 and you should get:
x = -0.3037223067 which is the value of x.
Like I said, you were on the right track, you just needed to evaluate the logarithms and work with their values for a little while.