Aradioactive element has a half-life of 10 days. if 800 g of the element are now available in a laboratory, how much will remain after 25 days?

Can someone me my sister? she is in third grade. 50 points and brainlist! ones that are not answered. plz and thx!

The amount of money, in dollars, in an account after t years is given by a = 1000(1.03)^t. the initial deposit into the account was $_^a0 and the interest rate was _a1% per year. only enter numbers in the boxes. do not include any commas or decimal points^t. the initial deposit into the account was $__^a0 and the interest rate is % per year.

Which of the following is the best first step in solving the equation below? 4+2㏒³x=17