Why is the answer d for question #49?

Elijah brought a total of 16 pounds of peanuts and cashew nuts and paid $49.50. if peanuts cost $2.75 per pound and cashew nuts cost $3.25 per pound, how many pounds of cashew nuts did he buy?

Afarmer sells 9.5 kilograms of apples and pears at the farmer's market. 4/5 of the weight is the apples and the rest is the pears. how many kilograms of pears did she sell at the farmers market

The number if marbles of different colors stored in a hat is listed below: 4 red marbles 10 green marbles 7 blue marbles. without looking in the hat, dan takes out a marble at random. he replaces the marble and then takes out another marble from the hat. what is the probability that dan takes out a blue marble in both draws?