Justin is considering two websites for downloading music. the costs are detailed here. website 1: a yearly fee of $30 and $1.50 for each download website 2: $2 for each download what is a system of equations to represent the costs for one year? express your equations in the form of y=mx+b where x is the number of downloads for the year and y is the total cost for the year.

Aman is 6 feet 3 inches tall. the top of his shadow touches a fire hydrant that is 13 feet 6 inches away. what is the angle of elevation from the base of the fire hydrant to the top of the man's head?

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

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.