9514 1404 393
Answer:
The sum is a binomial with a degree of 3.
Explanation:
The sum is ...
(6s²t -2st²) +(4s²t -3st²) = s²t(6 +4) +st²(-2 -3)
= 10s²t -5st² . . . . . . . a binomial of degree 3
__
The degree of the polynomial is the maximum sum of the degrees of the variables in each term. The first term is degree 2+1 = 3; the second term is of degree 1+2 = 3. The degree of the binomial is 3.