From 17 tosses, there are exactly 17C12 (C stands for combination) ways to get exactly 12 heads, that is 6188 ways. And we have 0.58 to get each of those head outcomes, and so 0.42 to get the rest of the outcomes (chance to get tail).
Thus, the probability to get exactly 12 heads is
6188 * (0.58)^12 * (0.42)^5 = 0.1172
