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 
