On the horizontal line y = 5, there are two points exactly 5 units from the point (7, 1). What is the sum of the x-coordinates of these two points?

14

Step-by-step explanation:

The two points on y=5 are (4,5) and (10,5), which can be deducted if you draw a picture with (7,1) and y=5 on it. A vertical line through 7,1 and the line to "some" points on y=5 left and right of it have lengths 4 and 5 respectively.

Then I realized these were two 3,4,5 triangles! So the x coordinates must be at 7-3=4 and 7+3=10 respectively!

The sum of 4 and 10 is 14.

edit: seems to me the sum is 14 regardless of the length of 5??