Odpowiedź :
50g 20%.....................100 - 30 = 70
........................30%
xg 100%.......................30 - 20 = 10
50/x = 70/10
70x = 500
x = 7,14g
50g 20%.....................100 - 30 = 70
........................30%
xg 100%.......................30 - 20 = 10
50/x = 70/10
70x = 500
x = 7,14g