Answer:
Using the exponent rule that a^m * a^n = a^(m+n), we can simplify the numerator:
x^38 * x^45 = x^(38+45) = x^83
So now the expression becomes:
x^83 / (x^10 * y^21)
Next, we can use the exponent rule that a^m / a^n = a^(m-n) to simplify the fraction:
x^83 / (x^10 * y^21) = x^83 / x^10 / y^21 = x^(83-10) / y^21 = x^73 / y^21
So the final simplified expression is x^73 / y^21.
Hope this helps!