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-2x = 43 - 36 = 7

Hence, is the required solution.

Example: Solve the following system of equations using substitution method:
x + y = a + b
2
2
ax - by = a - b
Solution: The given system of equations is
x + y = a + b (i)
2
2
ax - by = a - b (ii)
From (i), we get,
y = a + b - x (iii)
Putting y = a + b - x in (ii), we get,
2
2
ax - b(a + b - x) = a - b

2
ax + bx = a + ab
(a + b)x = a(a + b)

Putting x = a in (iii), we get,
y = a + b - a
y = b
Hence, x = a, y = b is the required solution.

NCERT Exercise 3.3- Q.3 (v)

A fraction becomes , if 2 is added to both the numerator and the denominator. if 3 is

added to both the numerator and the denominator it becomes . Find the fraction by

solving the system of equations by Substitution method.

Solution: Let the numerator be and the denominator be .

Then required fraction =

According to the given conditions we have,

………………………….(i)

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