A trapezoid's area is found using the formula A = 1/2 (a+b)h where a and b are the two bases. Substitute A = 12,052.1, a = 82.4 and b=108.6. Then solve for h.
Since you have to mix all of it together, the whole cocktail is 20+10+15=45. And the portion that is coconut milk is 15ml. So that means there is 15 out of 45 or 15/45 coconut milk in the cocktail. Then the simpelest form is 1/3.