Answer
The student did this to clarify which terms were being multiplied. By putting $x^3$ over 1, the student can see clearly that the 7 multiplies the $x^3$ and not the $x$.
Work Step by Step
The student did this to clarify which terms were being multiplied. By putting $x^3$ over 1, the student can see clearly that the 7 multiplies the $x^3$ and not the $x$.
$\frac{7}{x} \times \frac{x^3}{1} = \frac{7 \times x^3}{x \times 1}$
