ms1 = 50 g , c%1 = 20%
c%2 = 23% si stim ca c% = mdx100/ms
=> md1 = ms1xc%1/100 = 50x20/100 = 10 g
md2 = md1 + a , a = masa de soda adaugata
=> ms2 = ms1 + a
=> 23 = (10+a)x100/(50+a)
=> 23(50+a) = 1000 + 100a
=> 1150 + 23a = 1000 + 100a
=> a = 1,95 g soda adugata
facem proba:
ms2 = ms1+a = 51,95 g
md2 = md1+a = 11,95 g
=> c%2 = 11,95x100/51,95 = 23%........deci se probeaza