To answer this question, we will set and solve a system of linear equations.
Let x be the length of route X, and y be the length of route Y. In one week Cyd drove route X five times and route Y three times, therefore, we can set the following equation:
In another week, she drove route x twice and route y seven times, therefore:
Solving the second equation for x, we get:
Substituting the above result, in the first equation, we get:
Solving the above equation for y, we get:
Now, we substitute y=43 in x=(363-7y)/2 and get:
Answer: x is the length of route X, and y is the length of route Y.