The distance between (x, 7) and (1, 15) is 10, then x=?

(x,7)   $\overline{<----10---->}$  (1,15)

(x_1, y₁)                                                                          (x_2, y₂)    

Distance (d)=$\sqrt{{(x_2-x_1)}^2+{(y_2-y_1)}^2}$

$\Rightarrow 10=\sqrt{(1-x{)}^2+(15-7{)}^2}$

$\Rightarrow 10=\sqrt{(1-x{)}^2+64}$

Square both side

100=(1 - x)² + 64

(1 - x)² = 100 - 64 = 36

1 - x = $\sqrt{36}$= 6

x = 1-6

x = -5

The answer is option D.