My math section was EXCLUSIVITY "systems of linear equations" an engineering major helped me in that area, but you should easily study and become lightning quick at solving them.
for instance: (find x and y)
2x+4y=25
8x-3y=5
I consider myself very quick and accurate at all kinds of math, but was 2 short of finishing the math section on the astb. Study Study Study, and get your speed as fast as possible. They are going to throw more at you than you can handle. I studies for 2 solid weeks, at least 3 hours a day. Plus my Mech. Eng. degree and made a OAR 65. The place i spent most of my studying was areo/naut information, and it help tremendously as my supplemental was all areo/naut.
I had no electrical circuits on my mech comprehension. This section was cake. I think most problems are pretty intuitive, thats not to say skip studying, familiarize yourself with all the question types you can find, but this was deff the most intuitive part of the test.
Let me know if you have any more questions.