Answer
$\displaystyle \frac{3}{y}$
Work Step by Step
Step by step multiplication of rational expressions:
1. Factor completely what you can
2. Reduce (divide) numerators and denominators by common factors.
3. Multiply the remaining factors in the numerators and
multiply the remaining factors in the denominators. $(\displaystyle \frac{P}{Q}\cdot\frac{R}{S}=\frac{PR}{QS})$
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Factor what we can:
$9y+21=3(3y+7)$
$y^{2}-2y=y(y-2)$
The problem becomes
$...=\displaystyle \frac{3(3y+7)\cdot(y-2)}{y(y-2)\cdot(3y+7)}\qquad $... divide out the common factors
= $\displaystyle \frac{3}{y}$
