\VECTORADD(1,-1,2)(3,5,-1)(\sola,\solb,\solc)
$(1,-1,2)+(3,5,-1)=(\sola,\solb,\solc)$

\VECTORSUB(1,-1,2)(3,5,-1)(\sola,\solb,\solc)
$(1,-1,2)-(3,5,-1)=(\sola,\solb,\solc)$