Nomor 2 tolong dijawab... Terima kasih... Jawab yg benar!!

a. 13a-8b+21a+9b=13a+21a-8b+9b=34a+b
b. 15i-14j+13k-30i-45j+51k=15i-30i-14j-45j+13k+51k=-15i-59j+64k

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

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

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

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