f of g = 6(2x-1) - 5
12x - 6 - 5
12x - 11
Instead of just multiplying the binomials, f of g implies actually substituting the value of g for every appearance of x in the value of f. If it asked for g of f, you would substitute the x in 2x - 1 with 6x - 5, so it would be 2(6x-5) - 1.
