Question 1103264
One would think on first consideration that you might need to know how far apart they are, but you don't.
https://www.algebra.com/algebra/homework/Triangles/Triangles.faq.question.178260.html

https://www.wyzant.com/resources/answers/65227/exactly_how_far_above_the_ground_do_the_ropes_cross

https://www.mathhomeworkanswers.org/220727/vertical-heights-stretched-bottom-other-exactly-above-ground

They cross at the product over the sum (7*12)/(7+12)