The horizontal $x-$axis is drawn through the centroid $C$ of the area shown, and it divides the area into two component areas $A_1$ and $A_2.$ Determine the first moment of each component of area with respect to the $x-$axis if $w=58mm$ and $b=29mm.$

Dimensions in mm

The first moment of the area above the $x-$axis is ${10}^{3}m{m}^3.$

The first moment of the area below the $x-$axis is ${10}^{3}m{m}^3.($Include a minus sign if necessary.$)$