Answer
7400
Work Step by Step
$3785\approx3800\ \longrightarrow$ tens position is 5 or greater, round up
$648\approx600\ \ \ \ \ \longrightarrow$ tens position is not 5 or greater, round down
$2866\approx2900\ \longrightarrow$ tens position is 5 or greater, round up
$\ \ \ \overset23800$
$\ \ \ \ \ 700$
$\underline{+2900}$
$\ \ \ 7400$
