Question 456455
{{{ P = 2w + 2l }}}
You might want to write it as:
{{{ P = w + w + l + l }}}
given:
{{{ P = 78 }}} cm
{{{ w = 12 }}} cm
Substituting:
{{{ 78 = 12 + 12 + l + l }}}
{{{ 78 = 24 + 2l }}}
Subtract {{{ 24 }}} from both sides
{{{ 54 = 2l }}}
{{{ l = 27 }}}
The length is 27 cm