Divide both sides by 49/36 to get y by itself:


Simplify this fraction:

Now you have your answer:
Another way to solve this is to use the Midpoint Formula. The midpoint of a segment joining points

and

is

So the midpoint of your segment is

Perhaps it helps to see that the x-coordinate of the midpoint is just the average of the x-coordinates of the points. Ditto for the y-coordinate of the midpoint; just average the y's.
Do you need the expanded notation form, or expanded factor form?