It's simple, to solve for x(or any variable) you must do the opposite of what is being done, thus inverse operations. In your case k is being divided, so the inverse would be multiplication. However it does get much more complicated as the equations add more variables and operations. Seriously dude, pay attention. Everything you do in future courses with the slightest bit of math are going to require this basic set of skills. Math is a progressive skillset, and if you skimp out at the basics you'll only make it so much harder on yourself as you progress in high school.

Honestly this is probably not a great learning environment, or at least it's a redundant one. There are lots of sites purely dedicated to teaching students this sort of thing, and even communities for it.

This is the first google result I found:
http://tutoring.sylvanlearning.com/n.../0704/math.cfm
http://www.wtamu.edu/academic/anns/m...b/beg_algebra/