Abowl contains 10 quarters, 20 dimes, 15 nickels, and 5 pennies. a coin is selected at random and kept and then a second coin is selected at random. which combination would have a probability of 6/49?

In this question, there are a few kinds of the coin with a different value. To answer this question, we need to know the total coin first. The total coin count should be: 10 +20 + 15 +5= 50 coin

In this case, the coin is taken twice, that means the denominator should be 50*49. But in this question, the probablity value is 6/49, so you need to convert it into 50*49 by multiplying the numerator with 50. The value should be:
6/49 *50/50= 300/49*50
The number 300 is multiplication of 20 and 15, that mean the answer should be: 1 dimes and 1 nickles

For the first question the answer is a, for the second c, for the third d, for the 4th b, for the 5th a