Ben is 4 times as old as ishaan and is also 6 years older then ishaan. How old is ishaan

Describe all the numbers that when rounded to the nearest thousand are 645,000

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

Ivan and jeff buy a package of 8 pens for $4.00. ivan wants 5 of the pens, and jeff wants 3.how much should each student pay?