From my research the given equations are:
30x + 30y = 450
20x + 25y = 345
The problem asks to solve for the number of square feet Paul has shoveled more than Melinda. This can be solved by using the system of equations to solve for the values of x and y (the respective values of how each they have shoveled each).
Using the system of equations, the following values were obtained:
x = 6
y = 9
Therefore, Paul has shoveled 3 square feet per minute more than Melinda.