1) 10^10 / (x^10/x^5) = 10^10 / x^(10-5) = 10^10 / x^5
2) x^18 / (x^9/x^7) = x^18 / x^(9-7) = x^18/x^2 = x^(18-2)=x^16
3) x^6 / (x/x^5) = x^6 / x^(1-5) = x^6 / x^(-4) = x^6 * x^4 = x^10
4) (x^4/x^3) / (x^3/x^2) = x^(4-3) / x^(3-2) = x^1/x^1 = 1
5) (x^16/x^8) : x^4 : x^2 = х^(16-8) * x^(-4) * x^(-2) =
= x^(8 +(-4)+(-2))= x^2