keeping in mind that there are 12 inches in 1 foot, therefore 120' is 120*12 inches, namely 1440".
so, 120' 3½" is really just 1440" + 3" + ½", or 1443½".
then if we just subtract 7" from that, we end up with 1436½".
and we can convert that to feet by simply dividing it by 12, which gives us [tex]\bf 119\frac{17}{24}'[/tex].
