R-7.3 How many walls were erased to construct the maze in Figure 7.3, not counting the start and finish walls? Figure 7.3: A maze de fined from a 30 x 30 square grid. R-7.3 How many walls were erased to construct the maze in Figure 7.3, not counting the start and finish walls? Figure 7.3: A maze de fined from a 30 x 30 square grid