Solve for a
a=4\sqrt{5}+21\approx 29.94427191
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5a=20\sqrt{5}+105
Square both sides of the equation.
\frac{5a}{5}=\frac{20\sqrt{5}+105}{5}
Divide both sides by 5.
a=\frac{20\sqrt{5}+105}{5}
Dividing by 5 undoes the multiplication by 5.
a=4\sqrt{5}+21
Divide 105+20\sqrt{5} by 5.
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