Answer:
D 
Explanation:
1) rewrite 7 plus as 
7 + 
2) rewrite “the product of 9 and a“ as 
9a remembering that a product can be written without a sign that indicates the operation 
3) match the two informations 
7 + 9a 
4) rewrite “is 7” as: 
= 7 
5) write the final expression 
7 + 9a = 7