Let the height be 2x.
Thus, the base will be 3x.
formula for area of triangle is 1/2 * base * height. Thus, we have:
1/2 * 3x * 2x = 108
1/2 * 6x^2 = 108
6x^2 = 108 * 2
6x^2 = 216
x^2 = 216 / 6
x^2 = 36
x = sqrt(36)
x = 6
Base = 3x = 3(6) = 18 inches
Height = 2x = 2(6) = 12 inches