a) [tex] \frac{5}{12}+ \frac{3}{20}+ \frac{4}{15} = \frac{5*5+3*3+4*4}{60} = \frac{25+9+16}{60}= \frac{50}{60}= \frac{5}{6} [/tex]
b) [tex] \frac{11}{20}+ \frac{7}{10} + \frac{5}{16}= \frac{4*11+8*7+5*5}{80}= \frac{44+56+25}{80}= \frac{125}{80} =1 \frac{45}{80} [/tex]
c) [tex] \frac{16}{21} + \frac{3}{28}+ \frac{1}{42}= \frac{4*16+3*3+1*2}{84}= \frac{64+9+2}{84}= \frac{75}{84}/3 = \frac{25}{28} [/tex]
d) [tex] \frac{8}{15} + \frac{11}{18} + \frac{4}{45}= \frac{6*8+11*5+4*2}{90} = \frac{48+55+8}{90}= \frac{111}{90} /3= \frac{37}{30}= 1\frac{7}{30} [/tex]
e) [tex] \frac{17}{32}+ \frac{1}{24}+ \frac{7}{12}= \frac{3*17+1*4+8*7}{96}= \frac{51+4+56}{96}= \frac{111}{96} /3= \frac{37}{32} = 1\frac{5}{32} [/tex]
