Question 269843
The perimeter formula is
{{{P = a + b + c}}}
from above, we get
{{{P = 60}}}
{{{a = b - 6}}}
{{{c = 3a - 6}}}
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putting all of this together we get
{{{60 = b - 6 + b + 3b - 24}}}
combine like terms and we get
{{{60 = 5b -30}}}
add 30 to get
 {{{90 = 5b}}}
divide by 5 to get
{{{b = 18}}}
this means that 
{{{a = 12}}}
{{{c = 30}}}