No.2 Tolong dibantu yaa

a.=(13a-8b)+(21a+9b)
=13a-8b+21a+9b
=13a+21a-8b+9b
=34a-b

b.=(15i-14j+13k)+(-30i-45j+51k)
=15i-14j+13k+(-30i)-45j+51k
=15i-30i-14j-45j+13k+51k
=-15i-59j+64k

c.=(3x-17y+35z)+(4x+23y-9z)
=3x-17y+35z+4x+23y-9z
=3x+4x-17y+23y+35z-9z
=7x-6y+26z
Semoga Membantu