The chance of choosing a white marble is 7/12 (amount of red marbles = 2 because there is no exact number, the problem only states there are more than one marble. To find probability, add all of the possible changes combinations of choosing a marble from the bag. ( 3 + 7 + 2 = twelve. After finding how many possible combinations there are, subtract the # of possible combinations from the # of marbles that are not white. ( 12 - 5 = 7 ). Finally, put the amour of white marbles next to the # of possible combinations. (7/12)
the numerator simplifies to 5a^3 and the bottom is 15a. we can use our exponent rules to subtract exponents, so it is 1/3(a^2). this simplifies to a^2/3.
