a)
\frac{2}{5}*1,5-\frac{3}{10}+0,7=0,4*1,5-0,3+0,7=0,6-0,3+0,7=0,3+0,7=1
b)
7\frac{1}{7}*0,07-5\frac{5}{8}*1,6=\frac{\not50^1}{\not7}*\frac{\not7}{\not100^2}-\frac{\not45^9}{\not8^1}*\frac{\not16^2}{\not10^2}=\frac{1}{2}-9*1=-8\frac{1}{2}
c)
-2,34*3\frac{11}{13}+1,26*5\frac{5}{9}=-\frac{\not234^{18}}{\not100^2}*\frac{\not50^1}{\not13^1}+\frac{\not126^{14}}{\not100^2}*\frac{\not50^1}{\not9^1}=-\frac{18}{2}+\frac{14}{2}=-9+7=-2
d)
\frac{3,07-\frac{3}{5}}{2\frac{3}{5}+2,34}=\frac{3,07-0,6}{2,6+2,34}=\frac{2,47}{4,94}=\frac{247}{494}=\frac{1}{2}
e)
\frac{-2,7-1\frac{2}{3}}{-18\frac{1}{2}+5,4}=\frac{-\frac{27}{10}-\frac{5}{3}}{-18,5+5,4}=\frac{\frac{-81-50}{30}}{-13,1}=\frac{-\frac{131}{30}}{-\frac{131}{10}}=\frac{\not131^1}{\not30^3}*\frac{\not10^1}{\not131^1}=\frac{1}{3}
f)
\frac{11,2-3\frac{3}{5}}{11\frac{2}{5}+19}=\frac{11,2-3,6}{11,4+19}=\frac{7,6}{30,4}=\frac{76}{304}=\frac{1}{4}