Question

Please answer this question​

Answer 1

Step-by-step explanation:

$a) \: - \frac{3}{7} a \: \: \times \: - \frac{21}{15} b$

$= \frac{ 3}{5} ab \: (ans)$

$b) \: 3xy(5 {x}^{2} {y}^{2} - 4yz)$

$= 3xy \times 5 {x}^{2} {y}^{2} - 4yz \times 3xy$

$= 15 {x}^{3} {y}^{3} - 12x {y}^{2} z \: (ans)$