Question 291506
When calculating ratios use {{{ a/b = c/d }}} and cross multiply such that ad = bc <br>
{{{ 12/30 = 18/x }}}<br>
{{{ 12x = cross(30*18) = 540 }}}
{{{ 12x/12 = 540 / 12 }}}
x = 45 inches
and bob's your uncle!