If the block is held in the equilibrium position shown, determine the mass of block D$.$

The unstretched length of spring AB is $6$ m$.$

d$1=7$ m

d$2=9$ m

KAC $=54($ N$)/($m$)$

KAB $=97($ N$)/($m$)$

Block mass D $=\_()\_(\_())\_($ k$)$g