Question

a+b+c=243 a:c=12 r7 b:c=5r2

Answer 1

$a+b+c=243 \\\\ a:c=12 \ rest \ 7 \\\\ a=12c+7 \\\\\\ b:c=5 \ rest 2 \\\\ b=5c+2 \\\\\\ 12c+7+5c+2+c=243 \\\\ 18c=243-9 \\\\ 18c=234 \ \ \ |:18 \\\\ \boxed{c=13} \\\\ a=12*13+7 \\\\ a=156+7 \\\\ \boxed{a=163} \\\\\\ b=5*13+2 \\\\ b=65+2 \\\\ \boxed{b=67}$