Answer
$5x^4-8x^3-12x$
Work Step by Step
Recall the following rule: $\frac{a^{m}}{a^{n}}=a^{m-n}$
In order to solve this problem, use the rule above and cancel out common factors that are in both the numerator and the denominator of the fraction.
$=\dfrac{35x^6}{7x^2} - \dfrac{56x^5}{7x^2}- \dfrac{84x^3}{7x^2}
\\=5x^{6-2}- 8x^{5-2}-12x^{3-2}
\\=5x^4-8x^3-12x$
