Help me find post malone's circle?

It costs 4.25 for 1 pound of roast beef. how much will it cost to purchase 2.5 pounds of roast beef? round to nearest cent

Answer this question! 30 points and brainliest!

Apatient is given 50 mg dose of medicine the medicines effectiveness decreases every hour at a constant rate of 40% what is the exponential decay function that models this scenario how much medicine will be left in the patients system after 2 hours