If the passing of 5 half-lives leaves 25.0 mg of a Sr-90 sample, how much was present in the beginning?

they include patterns; cause and effect; scale, proportion, and quantity; systems and system models; energy and matter; structure and function; and stability and change.

can i get the brainiest answer

i answered it first

idk i’m struggling too

while cooking a piece of 1/2 pound beef steak, a cast iron pan (2.4kg in weight) was heated 260 celsius.