$($a$)$

Calculate the buoyant force $($in N$)$ on a $2\mathrm{.}50$ L helium balloon.

N $($upward$)$

$($b$)$

Given the mass of the rubber in the balloon is $1\mathrm{.}60$ g$,$ what is the net vertical force $($in N$)$ on the balloon if it is let go$?$ You can neglect the volume of the rubber.