Plz solve it correctly step by step!

Answer:
[tex]\dfrac{6}{10}ab[/tex]
Step-by-step explanation:
Given that,
The first number is [tex]\dfrac{-3a}{7}[/tex]
The second number is [tex]\dfrac{-21b}{15}[/tex]
We need to find the product of the first number and second number. Product means we need to multiply i.e.
[tex]\dfrac{-3a}{7}\times \dfrac{-21b}{15}=0.6ab\\\\=\dfrac{6}{10}ab[/tex]
Hence, the product of the given numbers is equal to [tex]\dfrac{6}{10}ab[/tex].