a si b sunt direct proportionale deoarece:
a/b = 3/2 = 9/6 =3/2 = 3/10 / 2/10 = 3/2 = 3/2 / 1 = 3/2 = 4,5/3 = 1,5 = 15/10 = 3/2 = 6/9 = 2/3
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x si y sunt invers proportionale deoarece:
X 3 2/5 6 18 3,6 9
Y 24 180 12 4 20 8
x*y=3*24=72=2*180/5=2*36=72=6x12=72=18*4=72=3,6*20=72=9*8=72