Intermediate Algebra
Yes — because both terms consist of the same base variables, a and b, and the coefficients determine whether they can be combined.
Yes — because the total degree (sum of exponents) is the same for both terms, which is the only requirement for like terms.
No — because coefficients with different signs cannot be combined, and since one is negative they must remain separate terms.
No — the exponents of a and b differ between the two terms, so their variable-exponent structures are different.