Alex was counting his coins by 2s. because one coin was left over he counted them by 3s. again there was one coin left over so he counted by 4s the 5s the 6s and finally 7s. each time there was one left over. knowing that alex did not have more than 800 coins exactly how many coins did he have

Can someone me out here number 4 plz

What is the quotient of m^6/5 ÷ 5/m^2? assume m does not equal pl

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.