What are the two things do you need to write an equation?

When asked to write an equation, you need to know two things – slope (m) and y-intercept (b).

Or

The Standard Form for a linear equation in two variables, x, and y, is usually given as Ax + By = C where, if at all possible, A, B, and C are integers, and A is non-negative, and, A, B, and C have no common factors other than 1.