Question

When solving a system of equations graphically, when

Answer 1

The grid lines will help you find an exact solution (assuming the two lines actually cross at a grid intersection point). However, the two lines may intersect somewhere off the grid lines which is when an estimation will be the next best thing.

Answer 2

Graphs in which both the x- and y-values for the intersection point are not integers need to be estimated because the lines do not intersect on a grid line where it is easy to read what the values are.