From one settlement to another 4 km away, John walked 1 km / h faster than going back. So on the way back, it took 12 minutes longer. Solving which equation would we know at what speed John was going if we denoted that speed x km / h? A. 4x − 1−4x = 15

B. 4x − 1−4x = 12

C. 4x + 1-4x = 15

D. 4x − 4x − 1 = 12

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?