[tex](3\frac{1}{2})^{2}:1\frac{3}{4}-(4+\frac{1}{2})(\frac{2}{3})^{2}=(\frac{7}{2})^{2}*\frac{3}{7}-(\frac{9}{2})(\frac{4}{9})=\frac{21}{7}-\frac{2}{1}=\frac{21-14}{7}=\frac{7}{7}=1[/tex]
[tex]\frac{4}{x}=\frac{20}{35}=>x=\frac{4*35}{20}=\frac{140}{20}=7[/tex]
36% ..........9 elevi
100% .........x elevi
x = 100×9/36 = 900/36 = 25 elevi
(a + b + c)/3 = 12 => a + b + c = 3×12 = 36
(b + c)/2 = 10 => b + c = 2×10 = 20
a = (a + b + c) - (b + c) = 36 - 20 = 16
a = 16
