Two points X and Y in the xy plane have coordinates (10,5) and (a,b), respectively. The midpoint of the line segment XY has coordinates (13,13). What is the value of a+b?

To find the midpoint of a line segment, you can use the midpoint formula:

Midpoint = (($x_1$ + $x_2$) / 2, ($y_1$ + $y_2$) / 2)

Given that the midpoint of the line segment XY is (13,13), you can equate the coordinates:

(13, 13) = (($10$ + a) / 2, ($5$ + b) / 2)

Now, let's solve for a and b.

From the x-coordinate of the midpoint, we have:

(($10$ + a) / 2) = 13

Multiply both sides by 2:

$10$ + a = 26

Now, subtract 10 from both sides:

a = 26 - 10 = 16

From the y-coordinate of the midpoint, we have:

(($5$ + b) / 2) = 13

Multiply both sides by 2:

$5$ + b = 26

Now, subtract 5 from both sides:

b = 26 - 5 = 21

Therefore, the value of a + b is:

a + b = 16 + 21 = 37

So, the value of a + b is 37.