This video looks at what it means to be a simultaneous equation. Looking at the ways you can express linear equations we then look at how to write these in a form to be able to find the two unknowns. Knowing that we are dealing with straight lines, we also look at the cases where lines might be parallel (and hence have no solution) or be the same line (and hence have one solution). Using methods of elimination and substitution I show how to solve these. I finish by looking at how to use the CAS.