The horizontal distance, d, is the adjacent side of a triangle of which the kite length is the hypotenuse, so
cos(40°) = d/25
Multiply both sides by 25
d = 25*cos(40°) feet
$${\mathtt{d}} = {\mathtt{25}}{\mathtt{\,\times\,}}\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{cos}}{\left({\mathtt{40}}^\circ\right)} \Rightarrow {\mathtt{d}} = {\mathtt{19.151\: \!111\: \!077\: \!975}}$$
d ≈ 19.15 feet