I need to figure out what c equals in the problem -3 - 3/4(c-4) =5/4
please help

Im literally having a mental breakdown

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?

Precalculus question, image attached.