(20v^2 -9v^3)-(7v^3 -10v^4 -14v^2)

(20v^2 -9v^3)-(7v^3 -10v^4 -14v^2)

20v^2 -9v^3 -7v^3 +10v^4 +14v^2

10v^4 -9v^3-7v^3 +20v^2+14v^2

10v^4 -16v^3 +34v^2