Claire, what is a linear equation?? It's an equation where x and y grow or shrink at constant rates.
For example, if a plant grows a half inch a week, if h = the height and t = the time, h = (1/2)t.
This equation means that the plant grows at 1/2 inch EVERY week. If the plant grows 3/4 inch one week, the equation no longer works and we don't have a linear relationship.
Remember that distance = rate x time. You are looking for both the distance and the time where the two would meet. Set up your two equations with the two variables, modeling them after the equation above.
Since the distances are the same, you can set the two right sides equal to each other and solve for t. Then substitute that value into either equation to solve for d.
You should know how to graph a line. Think y = mx + b. Since the distance depends on the time, time will be your x-axis and distance will be your y-axis. Where your two graphed lines meet is your answer for what fits your two equations.