11. write an equation of the line in slope-intercept form.
12. write in point-slope form an equation of the line that passes through the point (−2,4) with slope −12.
14. you develop an app to students complete their homework. to earn money, you sell advertising space on the app’s main screen. an advertiser pays you $25 per month and an additional $0.003 each time the app is opened.
graph the linear equation that represents your monthly income y (in dollars) when the app is opened x times.
15. write an equation of a line that passes through the point (4,3) and is perpendicular to the graph of the equation y=−13x+4.
16. an online media service offers video and music downloads. each download of a song costs $1. each download of a video cost 3 times as much as the song download. you have a credit of $90. how many songs can you purchase after buying 15 videos?