Решите пж срочно 1 номер

а) $\frac{3a}{b} *\frac{b}{6a}=\frac{3}{6}=\frac{1}{2}$

б) $\frac{18m^{3}} {5n^{2}}* \frac{25n}{12m^{2}}=\frac{3m}{n} *\frac{5}{2}=\frac{15m}{2n}$

в) $6x*\frac{a}{3x^{2}}= \frac{2a}{x}$

г) $\frac{x^{2}-16} {8x^{3}} *\frac{4x}{x+4}=\frac{(x-4)(x+4)}{8x^{3}} * \frac{4x}{x+4}=\frac{x-4}{2x^{2}}$

д) $\frac{5-y}{2y} *\frac{3y^{2}} {y^{2}-25}= \frac{5-y}{2y} *\frac{3y^{2}} {(y-5)(y+5)}=-\frac{3y}{2y+10}$

е) $(3a-6b)*\frac{a+2}{a^{2}- 4b^{2}}=3(a-2b)* \frac{a+2}{(a-2b)(a+2b)}=\frac{3a+6}{a+2b}$