regula dreptunghiului:
14%---------------------> 25-c parti solutie 14%
l l
l c% l
l l
25%-------------------> c-14 parti sol. 25%
-----------------------------------------------
total = 25-c+c-14 = 11 parti sol. c%
11 parti ............. 25-c p. sol. 14% ..... c-14 sol. 25%
a g sol ................ m .............................. 2m
m = a(25-c)/11
2m = a(c-14)/11
25-c = 2(c-14)
25+28 = 2c+c
53 = 3c
=> c = 17,67%