We have 21 marbles...we are drawing with replacement
P(red, red ) = 6/21 * 6/21 = 2/7 * 2/7 = 4/49 true
P (blue, yellow) = 4/21 * 9/21 = 4/21 * 3/7 = 4/49 false
P (yellow, red ) = 9/21 * 6/21 = 3/7 * 2/7 = 6/49 false
P(green, green ) = 2/21 * 2/21 = 4/441 false
P (yellow, green ) = 9/21 * 2/21 = 3/7 * 2/21 = 6/147 = 2/49 true
P (red, blue ) = 6/21 * 4/21 = 2/7 * 4/21 = 8 / 147 true
BTW.....we don't have an "amount" of marbles....we only have a "number" of marbles !!!!
Second one
P (G/ S) = P(S and G) / P(S) = .32 / .50 = .64 = 64%