[tex]c) \\ xy + \frac{3}{5} xy \\ \frac{xy}{1} + \frac{3xy}{5} \\ \frac{5xy}{5 \: . \: 1} + \frac{3xy}{5} \\ \frac{5xy}{5} + \frac{3xy}{5} \\ \frac{5xy + 3xy}{5} \\ \frac{8xy}{5} \\ \boxed{\boxed{\boxed{ \frac{8}{5} xy}}} \\ e) \\ 10bc - 12bc + 7bc - 3bc \\ (10 - 12 + 7 - 3)bc \\ (17 - 12 - 3)bc \\ (17 - 15)bc \\ \boxed{\boxed{\boxed{2bc}}} \\ f) \\ \frac{1}{3} x {}^{2} y {}^{2} + \frac{4}{9} x {}^{2} y {}^{2} - \frac{5}{6} x {}^{2} y {}^{2} \\ \frac{x {}^{2} y {}^{2} }{3} + \frac{4x {}^{2} y {}^{2} }{9} - \frac{5x {}^{2}y {}^{2} }{6} \\ \frac{6x {}^{2}y {}^{2} }{6 \: . \: 6 } + \frac{2 \: . \: 4x {}^{2} y {}^{2} }{2 \: . \:9 } - \frac{3 \: . \: 5x {}^{2}y {}^{2} }{3 \: . \: 6} \\ \frac{6x {}^{2} y {}^{2} }{18} + \frac{8x {}^{2}y {}^{2} }{18} - \frac{15x {}^{2}y {}^{2} }{18} \\ \frac{6x {}^{2} y{}^{2} + 8x {}^{2}y {}^{2} - 15x {}^{2} y {}^{2} }{18} \\ \frac{ - x {}^{2}y {}^{2} }{18} \\ \boxed{\boxed{\boxed{ - \frac{1}{18} x {}^{2} y {}^{2} }}} \\ [/tex]

att. yrz