A bag contains twice as many red marbles as blue marbles, and the number of blue marbles is 88% of the number of green marbles. If g represents the number of green marbles, which of the following expressions represents the total number of marbles in the bag?

There are twice as many red marbles as blue marbles, so (red) = 2(blue).
The number of blue marbles is 88% of the number of green marbles, so (blue) = 0.88g.
Substitute this expression for blue marbles in the one above:
(red) = 2(0.88g)
(red) = 1.76g
The total number of marbles is equal to red plus blue plus green:
(red) + (blue) + 1g
1.76g + 0.88g + 1g = 3.64g