Final answer:
The expression 28z⁷ - 22w⁷ cannot be simplified since it consists of two separate terms with different variables raised to the same power. The correct simplified expression remains as it was originally presented.
Step-by-step explanation:
The expression 28z⁷ - 22w⁷ cannot be simplified because it is composed of two terms with different variables raised to the same power. Since there are no like terms, i.e., terms with the same variables raised to the same power, no further simplification is possible.
In algebra, simplification of an expression often involves combining like terms, but since 28z⁷ and 22w⁷ do not have the same variable part, they remain separate. The correct simplified expression remains the same as the original: 28z⁷ - 22w⁷.
The possible choices given by the student include expressions which either change the coefficients or the variables; these would not hold true to the original expression and thus are incorrect. The correct answer in this case is option b) 28z⁷ - 22w⁷.