Answer:
(5, 24)
Step-by-step explanation:
In order to find the midpoint of a line, you need two sets of coordinates. The formula to find the midpoint of a line is , where is the x-coordinate of one of the coordinates and is the x-coordinate of the second coordinate (and so on for and ).
In this question, we're not given the two sets of coordinates to find the midpoint from. But we are told there is an interval 1 < x < 9, so first we substitute x=1 into the equation of the line: × = 3 + 9 = 12. So one of the coordinates is (1, 12). Doing the same with x=9, will give us y = 24.
Now if we use the formula I've written above, we should get (5, 24).