Evaluate the following limits$.$ If needed, enter oo for $$ and $-0$ for $-.$

$($a$)\underset{x}{lim}\frac{6x^3-7x^2-3x}{6-11x-10x^3}=$

$($b$)\underset{x-}{lim}\frac{6x^3-7x^2-3x}{6-11x-10x^3}=$