-7y^2 +2y^3 -7y +4y^3 +6y^2 +4y^2 +3y. Ok.
First, combine -7y^2 with 6y^2 and with 4y^2. =
Second, combine 2y^3 with 4y^3. =
Last, combine the terms -7y and 3y. =
Combining meaning add.
Then, add all the sums of the like terms to get the answer. Answer is = 6y^3 +3y^2 -4y