Answer
Option C is correct.
There are 21 green and red marbles combined.
Step-by-step explanation
There are 30 marbles in the bag
40% are red
40% of 30 marbles = 0.4 × 30 = 12 red marbles.
30% are green
30% of 30 marbles = 0.3 × 30 = 9 green marbles.
30% are blue
30% of 30 marbles = 0.3 × 30 = 9 blue marbles.
The question then asks us to compute how many marbles are green and red combined.
There are 9 grren marbles and 12 red marbles, that is, there are (9 + 12) = 21 green and red marbles combined.
Hope this Helps!!!