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?

You are cycling around europe with friends. a cycling festival is starting soon in barcelona. it will take 4.5 hours to cycle there. how many minutes in total is this?

Ajar of gumballs contains 4 reds, 2 greens, and 6 blues. what is the probability of getting two blues in a row without replacement?

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?