b) 3*y+5*y = 8*y = 8y
c) 7*z+z = 8*z = 8z
d) 3*y+x+6*x+3*y = 6*y+7*x = 6y+7x
Odpowiedź:
7z+z=8z
3y+5y=8y
3y+x + 6x +3y = 7x + 6y