When calculating the intercept, it is generally acceptable to leave the improper fraction as it is. Improper fractions can provide more precise values, which are especially important in mathematical contexts like statistics or graphing.
For example, if you calculate an intercept of 7/3, converting it to a mixed number (2 1/3) may not only complicate future calculations but could also lead to confusion when interpreting the result. Improper fractions make it easier to apply operations in subsequent steps, such as when plotting points on a graph or inserting values into equations.
That said, if you’re presenting your results for a non-technical audience, it might be more useful to express the number as a mixed number for easier understanding. The decision ultimately depends on your audience and the context in which you’re presenting the results.