I am having a problem with one equation that is ab-cd=0. I am supposed to solve for c and have been stuck on it. Can anyone help me?

ab - cd = 0
cd = ab
c = ab / d

Are you sure that you are supposed to solve it? That's an expression associated with matrix algebra called the discriminet... and if ab - cd = 0, in the matrix (a b)
(c d)
Then the matrix is invertable

Determinant, not "discriminet" :p

Yeah sorry... was doing that lesson when I responded... but that aside did that help or were you supposed to solve it?

I think they were just looking for algebra, not matrices :)