You add all of the balls together first(24 in total) then if your looking for the probability that it’s not a blue or green ball you only have to look for the probability of it being a red ball. Which is 8/24 or 1/3 if you want to make it into a simple fraction.
45 because 1set equals 3 push ups and she did ten sets so 10sets equal 30 push ups and then her coach asked her to do 15 more so 30 plus 15 equals 45 so she did 45 push ups that day!
