In the west region of the us, the ratio of densely vegetated land to sparsely vegetated

in the west region of the us, the ratio of densely vegetated land to sparsely vegetated land is 11:1811:1811, colon, 18. in the central region of the us, the ratio is 3:13:13, colon, 1. what is the difference in percentage of densely vegetated land from the west region to the central region?