Answer:
11
Explanation:
First, set up an equation. Since all the blue marbles+red marbles+green marbles= total number of marbles, we have: x+4x+x-5=91.
x+4x+x-5=91
6x-5=91
6x=96
x=16
Since there are x-5 green marbles, we get the number of green marbles=16-5=11.