1: tickets for the battle of the bands went on sale this week. on the first day of sales, 45 adult tickets and 20 student tickets were sold for a total of $875. on the last day of ticket sales, 25 adult tickets and 40 student tickets were sold for a total of $775. let x represent the cost for each adult ticket and let y represent the cost for each student ticket. write a system of equations to model this scenario and solve that system to determine the cost of each adult ticket. first day of sales equation: last day of sales equation: what is the cost of each adult ticket? dollars.

If a and b are the measures of two first quadrant angles and sin a = 4/9 and sin b = 2/5 find sin(a+b).

Mary used 1/7 of a spool of ribbon to complete 4 projects. she used the same amount of ribbon on each project. how much ribbon did she use on each project?

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.