help

The sum of all possible values of is 28.

The distance between the points (x, 21) and (4, 7) is 10√2. Find the sum of all possible values of x.

10√2  is a hypotenuse of a right triangle, the longer leg is 14.                                                                                          The short leg     a = sqrt[(10√2)² - 14²] = 2

1/      x = 4 - a = 2

2/      x = 4 + a = 6

So, the sum of all possible values of x is 8