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Solve the following two variable Linear equation A/7+B/3=5, A/2-B/9=6
CBSE | Class 10 | Exercise 3.3 | Maths | Pair of Linear Equations In Two Variables | RD Sharma
Solve the following two variable Linear equation A/7+B/3=5, A/2-B/9=6

The given pair of equations are:

A/7+B/3=5…………………………. (i)

A/2-B/9=6………………………………..(ii)

From (i), we get

A/7+B/3=5

⇒3A+7B=\left( 5\times 21 \right) [After taking LCM]

⇒ 3A=105-7B

⇒ A=(105-7B)/3……. (iv)

From (ii), we get

A/2-B/9=6

⇒ 9A-2B=108 ……………………… (iii) [After taking LCM]

Now, substituting A in equation (iii) we get,

\begin{array}{l} 9[(105 - 7B)/3] - 2B = 108\\ 945 - 63B - 6B = 324 \end{array} [After taking LCM]

⇒ 945-324=69B

⇒ 69B=621

⇒ B=9

Now, putting the value of B in the equation (iv)

\begin{array}{l} A = (105 - 7(9))/3\\ A = (105 - 63)/3 = 42/3\\ A = 14 \end{array}

Thus, the value of A and B obtained are 14 and 9 respectively.

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