The graph of the line x+y=b intersects the line segment from (2,5) to (4,9) at its midpoint. What is the value of b?
Midpoint of (2, 5) , (4,9) =
[ (2 + 4) / 2, (5 + 9) / 2 ] = ( 3, 7)
So...... x = 3, y = 7
And x + y = 10 = b
+612 
