Step-by-step explanation:
a.
[tex] \frac{3}{4} \times \frac{1}{2} [/tex]
[tex] \frac{3}{8} [/tex]
Now
b.
[tex] \frac{4}{7} \times \frac{21}{40} [/tex]
Now here we can see 21 is 3 times of 7 and 40 is 10 times of 4 so
[tex] \frac{3}{10} [/tex]
Hope this helps.
