[tex](\frac{1}{20}+\frac{1}{10} -\frac{1}{5} )*(-20)=-\frac{20}{20}-\frac{20}{10} +\frac{20}{5} =-1-2+4=4-3=1[/tex]

[tex]15(-\frac{1}{3} -\frac{1}{5} -\frac{1}{15} )=-\frac{15}{3} -\frac{15}{5} -\frac{15}{15} =-5-3-1=-9[/tex]