An art teacher wants to do a project for her 12 seventh graders. Each student will need 2 feet of yarn. If the total is $18, write an equation to determine the cost of yarn, c, per foot.

So what am i supposed to do here? i am so lost. i don't know where all the #'s go. Someone please help. =/

12 * 2x = 18

Solve for x.