Решение 

`*`(50, `/`(1, 2)) = `+`(`/`(`*`(189), `*`(`+`(v, 2))), `/`(`*`(`+`(189, -50)), `*`(`+`(v, `-`(2)))))[[v = 0], [v = `/`(328, 25)]]`*`(328., `/`(1, 25)) 

13.12000000 (5.2.1)