Brittany, Alex, and Jamy all share 600 marbles divided between them in the ratio 3:5:7. If Brittany gives Alex half of her marbles, what's the total number of marbles that Alex has?
The total ratio representing the number of marbles is 3+5 +7 = 15
From the ratio, the fraction representing the number of marbles that Brittany has is 3/15, which is equal to 3/15*600 = 120 marbles.
Alex has 5/15*600 = 200 marbles.
If Brittany gives half of her marbles to Alex, Alex receives 1/2*120 = 60 marbles.
After receiving 60 marbles from Brittany, Alex has 200+60 = 260 marbles.