What is the volume of the composite figure page 512 chapter 11 4

What is sin 7x/4 ? i need on this urgent trig

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20

Lin is writing an equation to model the proportional relationship between y, the total cost in dollars of downloading videos from a website, and x, the number of videos downloaded. she knows that the total cost to download 3 videos was $12. her work to find the equation is shown below. joylin’s work step 1 k= 3/12= 0.25 step 2 y= 0.25x where did joylin make her first error?