An element has a half-life of 30 years. If you start with 10g of this element, how many grams of this element would remain after 60 years? show work

After two half-lives or 60 years, 7.5 g of the element will be left.

Explanation:

Half-life:

In simple words, Half-life can be defined as the amount of time needed for a quantity to fall to half its value as contained at the beginning of the time period. In this problem the half-life of the element is thirty years, then after thirty years half of the sample would have decayed and half would be left as it is. After thirty years (The first half-life ) 30 /2 = 15 g declines and 15 g remains disappeared. And after another sixty years (The two half-lives) 15 /2 = 7.5 g declines and 7.5 g remains disappeared. After two half-lives or 60 years, 7.5 g of the element will be left.

Although i don't know what is the simulated system, starfish are predators that eat mostly  microalgae,  snails, sponges, bivalves, mussels and other small marine animals. removing starfish from any system would definitely increase this animals that they prey.