Part a.
Let x be the unknown number. Then, the statement "the product of a number and 2" can be written as
[tex]2x[/tex]
since this product must be equal to 16, we have
[tex]2x=16[/tex]
Then, the answer is the second option: 2x=16.
Part b.
In this case, we need to isolate the x variable. Then, by dividing both side of our last result, we get
[tex]x=\frac{16}{2}[/tex]
which gives
[tex]x=8[/tex]
Therefore, the answer for b) is: 8
