-3d+1/3(6+3d)=-10
-3d + 2+d =-10
-2d=-12
d=6
-3d+2+d= -10
-2d+2= -10
just thought this step should be shown :)
-2d= -12
d=6
-3d + 2+d =-10
-2d=-12
d=6
-3d+2+d= -10
-2d+2= -10
just thought this step should be shown :)
-2d= -12
d=6