I'll solve 1,2, 8, and 9 and then you can use those techniques to solve the rest.
For 1, we subtract 9 from both sides to separate the 3f and get 3f<12. Dividing both sides by 3, we get f<4
For 2, we add 3 to both sides to get 4n ≥ 108 and dividing by 4 we get n ≥ 27
For 8, we can start off by expanding using the distributive property, getting 12c-15-2c >0. Next, we get 10c-15>0 and adding 15 to both sides we get 10c> 15. After that, we divide both sides by 10 to get c > 15/10 = c> 1.5
For 9, we expand again to get 15j-45+3j < 45. Next, we add 45 to both sides and add from there, getting 18j < 90. Next, we divide both sides by 18 to get j < 5
