3.2x3 + 4.8x +3.7
2.1x3 +6.3x - 2.9

Answer:
5.3x^3+11.1x+0.8
Step-by-step explanation:
Add ones with similar variables
5.3x^3+11.1x+0.8
Answer: 5.3x^3 + 11.1x + 0.8
:D
I hope this helps! :)