Final answer:
The equivalent expression to 7z + 9z is 2z + 5z + 9z, all of which simplify to 16z when like terms are combined.
Step-by-step explanation:
The expression 7z + 9z is equivalent to 16z because when you combine like terms (terms with the same variable part), you simply add their coefficients (the numerical part). In this case, 7 + 9 equals 16, so 7z + 9z becomes 16z.
Looking at the options provided, we can rewrite each one as follows:
- 2z + 5z + 9z = 2z + 14z = 16z
- 10z + 5z = 15z
- 13z + 2z = 15z
Therefore, the expression that is equivalent to 7z + 9z is 2z + 5z + 9z, which also equals 16z.