You can put this solution on YOUR website! tan 75 = tan (45 + 30). tan (a + b) = (tan a + tan b)/(1 - tan a * tan b). So your problem, tan 75 = tan (45 + 30) = (tan 45 + tan 30)/(1 - tan 45 * tan 30).
45 and 30 are special angles, so you should know them; tan 30 = /3 and tan 45 = 1. Just plug these in and solve!