there are 12 slate rocks , 16 pumice rocks , and 8 granite rocks randomly distributed in a certain field . if 2 rocks are chosen at random and without replacement , what is the probability that both rocks will be slate rocks ?
12 / 36 * 11 / 35 = 11 / 105 the answer is c .
multiply(divide(12, add(add(12, 16), 8)), divide(subtract(12, const_1), subtract(add(add(12, 16), 8), const_1)))