Answer
$C = (-4.9~\hat{i}-1.9~\hat{j})~m$
Work Step by Step
$A+B+C = 0$
$C = -(A+B)$
$C_x = -(A_x+B_x)$
$C_x = -[4~m~cos(40^{\circ})+2~m~cos(20^{\circ})]$
$C_x= -4.9~m$
$C_y = -(A_y+B_y)$
$C_y = -[4~m~sin(40^{\circ})-2~m~sin(20^{\circ})]$
$C_y = -1.9~m$
$C = (-4.9~\hat{i}-1.9~\hat{j})~m$
