ANSWER
[tex]\frac{3}{7}(-21x-49)= -9x- 21[/tex]
EXPLANATION
To expand
[tex]\frac{3}{7}(-21x-49)[/tex], we use the distributive property of multiplication over subtraction.
According to the distributive property of multiplication over subtraction, if we have any three real numbers,
[tex]a,b,\:and\:c[/tex].
Then;
[tex]a(b-c)=a\times b-a\times c[/tex]
Applying this property to the given expression, we obtain;
[tex]\frac{3}{7}(-21x-49)= \frac{3}{7}\times (-21x)- \frac{3}{7}\times (49)[/tex]
If we cancel out common factors we obtain;
[tex]\frac{3}{7}(-21x-49)= 3\times (-3x)- 3\times (7)[/tex]
If we simplify further, we obtain;
[tex]\frac{3}{7}(-21x-49)= -9x- 21[/tex]
