A)
[tex]\frac{1}{2}+\frac{2}{3}+\frac{3}{4}[/tex]Find the LCM of 2, 3, 4
LCM = 12
The expression becomes:
[tex]\begin{gathered} \frac{6+8+9}{12} \\ =\text{ }\frac{23}{12} \\ =\text{ 1}\frac{11}{12} \end{gathered}[/tex]B)
[tex]\begin{gathered} \frac{2}{3}\times\frac{42}{5}\times\frac{10}{7} \\ =\text{ }\frac{2\times6\times2}{3} \\ =2\times2\times2 \\ =\text{ 8} \end{gathered}[/tex]