Answer:
[tex] \frac{15,4+14,5+13,1+12,3 + x}{5} = 14.2[/tex]
[tex] \frac{55.3 + x}{5} = 14.2 \\ [/tex]
[tex]11.06 + \frac{x}{5} = 14.2[/tex]
[tex] \frac{x}{5} = 3.14[/tex]
[tex] \frac{x}{5} = 3.14[/tex]
[tex]x = 3.14 \times 5 = 15.7[/tex]
the heaviest fish was 15.7
I hope it is right