Answer:
9 = 1 + 2n
Step-by-step explanation:
A sum is indicated with a plus sign (+). Two times a number is represented by the product of 2 and the variable used to represent the number. Here, we have chosen "n" (for "number"). Then the sum is ...
1 + 2n
"Is" in this context means "equals", so we have ...
9 = 1 + 2n
