21 would be the answer hope this helps :)

The formula for area of triangle is -

________________________________
So, the area of first triangle =



________________________________
Area of second triangle =



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Area of second triangle - Area of first triangle



Answer:
D
Step-by-step explanation:
Using the rule of radicals
= 
×
⇔ 
Given
× 
=
× 
=
× 
Cancel
on numerator/ denominator
=
× 
=
× 
Cancel
on numerator/ denominator, leaving
=
→ D
Answer:
Hey there!
You can think of the rate of change as the slope of a quadratic function- here we see that it is 9/-3, or - 3.
Let me know if this helps :)