A copy of an optimal (Euler) circuit, in PDF.
Essentially, the edges marked (1) give an optimal Eulerization. But the two edges marked (2) must be added in order to avoid going down a one-way street the wrong way. Without them, the vertices on both ends have more streets coming in (or out!) than out (or in!)

A solved copy of one of the practice tests (so, for example, you can get a sense of *how* answers can/should be typed) may be found here.
What you should note is that I made the *computer* do all of the arithmetic; you don't need to add or multiply or divide any number before you *write* your answer. The only hard part is that this makes the placement of parentheses ( ) very important... Note that "sqrt( )" means the square root of the stuff inside the parentheses.