mohon bantuannya cuman no.2

dik:
vektor a = (-8 , 4 )
2a + b = ( 13 , -5 )

dit:
vektor b?

maka:
2a + b = ( 13 , -5 )
2( -8 , 4 ) + b = ( 13 , -5 )
( -16 , 8) + b = ( 13 , -5 )
maka b = ( 29 , 13 )