Question 62285
{{{(-3/7)z=7/5}}}
{{{(-7/3)(-3/7)z=(-7/3)(7/5)}}}
{{{(21/21)z=-49/15}}}
{{{1z=-49/15}}}
{{{highlight(z=-49/15)}}}
Check:
{{{(-3/7)(-49/15)=7/5}}}
{{{(-3/7)((-7*7)/(5*3))=7/5}}}
{{{(cross(-3)/cross(7))(cross(-7)*7/(5*cross(3)))}}}
{{{7/5=7/5}}}  We're right.
Happy Calculating!!!