Well, we know that the x-intercepts are (0,2) and (0,4). That means that the midpoint is just (0,3)
You can also use the midpoint formula:

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Answer:
48
Step-by-step explanation:
Given: 
Now, solving it.
We first open parenthesis which is (b)
(17) = 
Next Multiply both side by 2
⇒ 816 = 
Now, we will divide both side by 17
∴ b