[tex]\it a = 1\dfrac{2}{3} = \dfrac{5}{3}
\\\;\\ \\\;\\
b= 2\dfrac{3}{4} =\dfrac{11}{4}
\\\;\\\\\;\\
c= 3\dfrac{4}{5} =\dfrac{19}{5}[/tex]
[tex]\it m_{a.p.}= \dfrac{3a+4b+5c}{3+4+5} = \dfrac{3\cdot\dfrac{5}{3}+4\cdot\dfrac{11}{4}+5\cdot\dfrac{19}{5}}{12} = \dfrac{5+11+19}{12}=\dfrac{35}{12}=
\\\;\\ \\\;\\
= 2\dfrac{11}{12}[/tex]
