Element X is a radioactive isotope such that every 81 years, its mass decreases by half. Given that the initial mass of a sample of Element X is 1800 grams, how much of the element would remain after 28 years, to the nearest whole number?

The dolphins at the webster are fed 1/2 of a bucket of fish each day the sea otters are fed 1/2 as much fish as the dolphins how many buckets of fish are the sea fed each day? simplify you answer and write it as a proper fraction or as a whole or mixed number

Divide. reduce the answer to lowest terms.5 2/3 ÷ 3 1/9

Use the data on the dot plot to answer the question.how many people read for more than three hours last week? i'm on a unit test review