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Mathematics

A number consists of two digits, the difference of whose digits is 5. If 8 times the number is equal to 3 times the number obtained by reversing the digits, find the number.

Linear Equations

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Answer

According to question,

Original number is smaller than the number obtained by reversing its digits.

∴ In original number, unit's digit greater than ten's digit.

Let the ten's and unit's digit of required number be x and y respectively y > x.

Given,

⇒ y - x = 5

⇒ y = x + 5     …..(1)

Number obtained by reversing the digits = (10y + x)

Given,

8 times the number is equal to 3 times the number obtained by reversing the digits.

⇒ 8(10x + y) = 3(10y + x)

⇒ 80x + 8y = 30y + 3x

⇒ 80x - 3x + 8y - 30y = 0

⇒ 77x - 22y = 0     …..(2)

Substituting the value of x from equation (2) in 77x - 22y = 0, we get:

⇒ 77x - 22y = 0

⇒ 77x - 22 × (x + 5) = 0

⇒ 77x - 22x - 110 = 0

⇒ 55x - 110 = 0

⇒ 55x = 110

⇒ x = 11055\dfrac{110}{55}

⇒ x = 2.

Substituting value of y in equation (2), we get :

⇒ y = x + 5

⇒ y = 2 + 5

⇒ y = 7.

Number = (10x + y) = 10 × 2 + 7 = 27.

Hence, the number is 27.

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