let the missing term be y
(x^12)^5 x (x^-2)^9 x y = (x^40)^5
(x∧60) x (x∧-18) x y = x∧200 (just multiply the powers together)
x∧60 ÷ x∧18 x y = x∧200 (just put the x∧-18 as divider (is that what it called) and the power will be positive)
x∧42 x y = x∧200 (cross out the x∧18 by minusing power 60 by 18)
y = x∧200 ÷ x∧42 (swapping the place)
y = x∧158