Final answer:
The mass of each emerald is approximately 0.571 times as great as the mass of each sapphire.
Step-by-step explanation:
To find out how many times as great the mass of each emerald is compared to the mass of each sapphire, we can divide the mass of the emerald by the mass of the sapphire.
Mass of emerald: 0.18 g
Mass of sapphire: 0.315 g
Now, divide the mass of the emerald by the mass of the sapphire:
0.18 g / 0.315 g = 0.571
Therefore, the mass of each emerald is approximately 0.571 times as great as the mass of each sapphire.