Помогите сократить дробь

Решите задачу:

$1) \frac{3a+12b}{6ab} = \frac{3*(a+4b)}{3*2ab}= \frac{a+4b}{2ab}$
$2) \frac{a^{2} -6a}{3 a^{2} } = \frac{a(a-6)}{3a*a} = \frac{a-6}{3a}$
$3) \frac{5 y^{2} }{8 xy^{2}-3 y^{2} } = \frac{5* y^{2} }{ y^{2} *(8x-3)} = \frac{5}{8x-3}$
$4) \frac{2 a^{2} b}{4 a^{2} -6ab} = \frac{2a*ab}{2a*(2a-3b)} = \frac{ab}{2a-3b}$
$5) \frac{xy-3x}{6y-18}= \frac{x*(y-3)}{6*(y-3)}= \frac{x}{6}$
$6) \frac{ac-5c}{3a-15}= \frac{c*(a-5)}{3*(a-5)} = \frac{c}{3}$