Answer
4 tons 1650 lb
Work Step by Step
Borrow one ton from the 8 tons. Subtract tons from tons and pounds from pounds.
$\ \ \ \overset7/\!\!\!8\ tons\ \overset2/\!\!1\overset9/\!\!\!0\overset{10}00\ lb$
$\underline{-3\ tons\ 1\,35\,0\ lb}$
$\ \ \ 4\ tons\ 1\,6\,50\ lb$