x = k - [(pq)^(1/2)]/y

transpose x to the right and transpose [(pq)^(1/2)]/y to the left

when you transpose, please change your sign to the opposite sign, that is (+ to -) and (- to +).

[(pq)^(1/2)]/y = (k - x)

cross-multiply, obviously y and (k - x) will change places

[(pq)^(1/2)]/(k - x) = y

or

y = [(pq)^(1/2)]/(k - x)

a latex print will be better to see, i'm too LAZY to learnlatex