[tex]-8,0(8)- \frac{5,7}{9}=-(8 \frac{8}{90}+ \frac{57}{90} ) =-( \frac{728}{90}+ \frac{57}{90} )=\\- \frac{785}{90} =- \frac{157}{18} [/tex]
[tex] \frac{2,1}{4}\cdot \frac{1,23}{45} = \frac{2,583}{180}= \frac{2583}{180000}[/tex]
[tex]-24:(- \frac{5,7}{13} )=24\cdot \frac{13}{5,7} = \frac{8\cdot13}{1,9} = \frac{104}{1,9} = \frac{1040}{19} [/tex]
[tex]-6,54\cdot(-3,21)=6,54\cdot3,21=20,9934[/tex]
[tex]-64,8: \frac{6,3}{4}=- \frac{64,8\cdot40}{63}= -\frac{7,2\cdot40}{7} = -\frac{288}{7} [/tex]
