[tex] 17 \frac{1}{7}= \frac{17*7+1}{7}= \frac{119+1}{7} =\frac{120}{7} [/tex] mere
[tex]23 \frac{1}{4}= \frac{23*4+1}{4}= \frac{93}{4}[/tex]
pere: [tex] \frac{120}{7}+ \frac{93}{4}= \frac{120*4+93*7}{7*4}= \frac{4011}{28} [/tex]
mere +pere [tex] \frac{4011+480}{28} = \frac{4491}{28} [/tex]