How can I solve this?

Write an equation of the function whose graph is described in words. The graph of y = cos(X) is vertically stretched by a factor of4 and shifted down by 9 units. One cycle of y = cos(X) on [0, 2n] is compressed to [0, n/3] and then the compressed cycle is shifted horizontally 7r/4 units to left. y= 4c0s(6x+ %)9 x