a bag contains 9 green and 8 white balls . if two balls are drawn simultaneously , the probability that both are of the same colour is
"drawing two balls of same color from nine green balls can be done in 9 c ₂ ways . similarly from eight white balls two can be drawn in ⁸ c ₂ ways . p = 9 c ₂ / ¹ ⁵ c ₂ + ⁸ c ₂ / ¹ ⁵ c ₂ = 8 / 17 answer : a"
add(multiply(divide(8, add(9, 8)), divide(subtract(8, const_1), subtract(add(9, 8), const_1))), multiply(divide(9, add(9, 8)), divide(subtract(9, const_1), subtract(add(9, 8), const_1))))