Answer 1

It is given that mid-point of line segment joining A (6, 5) and B (4, y) is P(x , 6) 

In general to find the mid-point P( x, y)  of two points`A(x_1 , y_1) " and B " ( x_2 , y_ 2)`  we use section formula as,

`P(x , y) = ((x_1 + x_2) /2 , (y_1 + y_2) / 2)`

So,

`(x , 6 ) = ((4+6)/2 , (y+5)/2)`

Now equate the y component to get,

`(y + 5)/2 = 6`

So,

 y = 7