Answer:
A
Step-by-step explanation:
To find the best equation, we simply substitute the values of a, b, and c into the given equations.
a = 21
b = 5
c = 36
[tex]a=\dfrac{7}{10}b\sqrt{c}[/tex]
[tex]21=\dfrac{7}{10}5\sqrt{36}[/tex]
[tex]21=\dfrac{7}{10}5(6)[/tex]
[tex]21=\dfrac{7}{10}30[/tex]
[tex]21=(0.7)30[/tex]
[tex]21=21[/tex]
