Ответ:

w = m вещества \m раствора *100%

1) w = 10\90*100% = 11,1%

2) w = 8\68*100% = 11,8%

3) w = 20\140*100% = 14,3%

4) w = 50\150*100% = 33,3%

5) w = 10\70*100% = 14,3%

6) w = 5\25*100% = 20%

7) w = 10\60*100% = 16,7%

8) w = 40\200*100% = 20%

9) w = 10\80*100% = 12,5%

10) w = 4\24*100% = 16,7%

11) w = 20\220*100% = 9,09%

12) w = 50\350*100% = 14,3%

13) w = 20\110*100% = 18,2%

14) w = 20\90*100% = 22,2%

15) w = 20\80*100% = 25%

Объяснение: