Find the missing term (x^12) ^5 * (x^-2) ^9___ = (x^40) ^5

(x^12) ^5=x^ (12*5) = x^60

(x^ (-2)) ^9=x^ (-18)

x^60*x^ (-18) = x^ (40) and we need to find x^a such that

x^ (42) * x^a=x^ (40) ^5

x^a=x^ (40) ^5*x^ (-42)

x^a=x^ (200) x^ (-42)

x^a=x^ (200-42)

x^a=x^158

so the missing term is x^158