What is the period of y=4cos5x

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

Ab based on the given diagram, if m_1 = 60° then m 2 = 30 60 90 180

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?