[tex] \frac{6}{12} * \frac{15}{35} * 2 = \frac{6*15*2}{12*35} = \frac{180}{420} = \frac{3*60}{7*60} = \frac{3}{7}[/tex]
[tex] \frac{-2}{7} * \frac{42}{16} * \frac{-18}{9} = \frac{2*42*18}{7*16*9} = \frac{1512}{1008} = \frac{3*504}{2*504} = \frac{3}{2} = 1.5[/tex]
[tex] \frac{3}{5} + \frac{4}{20} - 7 = \frac{3*4}{5*4} + \frac{4}{20} - 7 = \frac{12}{20} + \frac{4}{20} - 7 = \frac{16}{20} - 7 = 0.8 -7 = -6.2[/tex]
[tex] \frac{-3}{6} ( \frac{4}{9} - \frac{5}{3}) = \frac{-3*4}{6*9} - \frac{-3*5}{6*3} = \frac{-3*4}{6*3*3} + \frac{3*5}{6*3} = \frac{-4}{18} + \frac{15}{18} = \frac{11}{18}[/tex]
