2) - d
- d*3
- 3d+6
3) a) 3*3+6 = 9+6 = 15
b) 8*3+6 = 24+6 = 30
c) 1,2*3+6 = 3,6+6 = 9,6
d) 6,7*3+6 = 18,9+6 = 24,9
