Answer:
7a³-2b²
Step-by-step explanation:
[tex]8a^3-3b^2-(-a)^3+b^2=(8-1)a^3+(-3+1)b^2=7a^3-2b^2[/tex]
_____
Math symbols were invented so that expressions could be written unambiguously. You might find you are more likely to get the answers you need if you use them.