Question 1199590

A, of $1, a
B of $0.5, b
C, of $0.10, c

{{{system(a=5c,b=a-12,c=b/2)}}}


{{{a=5c,b=a-12,b=2c}}}

{{{a-12=2c}}}

{{{c=(a-12)/2}}}-------substitute this into the part, {{{a=5c}}}.


{{{a=5(a-12)/2}}}------the substitution


{{{2a=5(a-12)}}}

{{{2a=5a-60}}}

{{{3a=60}}}

{{{highlight_green(a=20)}}}-------------------makes for  $20 .