If each bag contains 10 MartianMallows, then 3 bags contain (3)(10)=30 MartianMallows. Since we know that the cost of 30 MartianMallows is 24 space rocks, we can set up the proportion 24/30=s/4, where s is the cost of four MartianMallows. Solving for s, we find that s=24/30*(4)={16/5 space rocks.
