Answer:
b. 11
Explanation:
You'll have two equations in this system. Let G represent George's marbles and M represent Miguel's marbles.
1. G+3=2M (George's marbles plus 3 equals twice of Miguel's)
2. G-4=M (George's marbles minus 4 equals Miguel's marbles)
We have an explicit M value, so we can use the substitution method. Substitute the second equation into the first for M: G+3=2(G-4).
After some algebra, you'll get G=11. George has 11 marbles.