Work out the volume of a pyramid please help i’ll give u brainlest

Iwill make brain if you me correctly fill this out needs due today pls and send it back to me (click the link and you will get it)

Simply 8x squared + 5(7x squared- x) - 2x =

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.