$19$

$3$ elementary students push on a tire swing. What is the net resulting force? $*[4.(2\mathrm{.}5$ Points$)$

$13$ lb $($up$)$

$4$ lb $($right$)$; $1$ lb $($up$)$

$3$ lb $($right$)$; $6$ lb $($up$)$

$3$ lb $($up$)$