Question 999537
This is the system, translated exactly according to the description:
{{{system(a=-10+b,c=10+b,c=3a)}}}


A simple rearrangement can be  {{{system(a=b-10,c=b+10,c=3a)}}}.  Various ways to solve the system for a, b, c.


{{{system(a=b-10,b+10=3a)}}}


{{{system(a=b-10,b=3a-10)}}}


{{{a=(3a-10)-10}}}


{{{a=3a-20}}}


{{{-2a=-20}}}


{{{highlight(a=10)}}}-------one of the values solved.