m(4i+Vj)+m(2i−Vj)=(m+m)(3i+2j)(4m+2m−3m)i+(mV−mV−2m)j=0i+0j
Consider the i component. That is the i component on the left hand side must be the same as the i component on the right hand side.
3m+2m−4=02−1=0=21
