Answer :
A)
3 1/5=3+1/5
[tex]x=8(3+\frac{1}{5})[/tex]Where x is the total length of the 8 pieces of wood.
Then,
[tex]\Rightarrow x=24+\frac{8}{5}=25+\frac{3}{5}[/tex]Jack is not correct; he just multiplied 8*24 rather than 24*(8 1/5)
B)
[tex]\begin{gathered} \frac{1}{2}(2+\frac{3}{4})=1+\frac{3}{8} \\ \text{and} \\ \frac{3}{4}(2+\frac{3}{4})=2+\frac{1}{16} \end{gathered}[/tex]Then, Jack used between 1+3/8 kg and 2+1/16 kg of nails