First we divide all of the ingredients by 18 to see how much we nee for one rock cake.
9 / 18 = 0.5
6 / 18 = 0.33
2 / 18 = 0.11
6 / 18 = 0.33
8 / 18 = 0.44
Now we multiply all of these by 12.
0.5 * 12 = 6 ounces of flour
0.33 * 12 = 3.96 ounces of margarine
0.11 * 12 = 1.32 large eggs
0.33 * 12 = 3.96 ounces of sugar
0.44 * 12 = 5.28 ounces of fruit