Question

30% of 18√a + 680 is 420.
Find the value of a
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Answer 1

Given :

$\bullet \tt \: 30 \% \: of \: 18 \sqrt{a} + 680 = 420$

To find :

$\bullet \tt \: the \: value \: of \: a$

solution :

$\\ \\ \implies\bf{ 30 \: percent \: \times 18 \sqrt{a}+680=420}$

$\\ \\ \implies\sf{\dfrac{30}{100}( \times 18 \sqrt{a} +680)=420}$

$\\ \\ \implies\sf{30 (18 \sqrt{a}+680)=4200}$

$\\ \\ \implies\sf{18 \sqrt{a}+680=\dfrac{4200}{30}}$

$\\ \\ \implies\sf{18 \sqrt{a}+680=1400}$

$\\ \\ \implies\sf{18 \sqrt{a}+680-1400=0}$

$\\ \\ \implies\sf{18 \sqrt{a}=720}$

$\\ \\ \implies\sf{\sqrt{a}=\dfrac{720}{18}}$

$\\ \\ \implies\sf{\sqrt{a}=40}$

$\\ \\ \implies\green{\underline{\sf{Squaring \: both \: sides}}}$

$\\ \\ \implies\sf{a=1600}$

$\\ \blue\bigstar{\boxed{\bf{The \: value \: of \: a \: is 1600}}}$

Answer 2

Solution:-

30percent of 18√a+680=420

30/100 ×(18√a+680)=420

3/10(18√a+680)=420

18√a+680=1400

18√a=720

√a=40

a=1600

hence the value of a is 1600