Question

Seven times a two digit number is equal to four times the number obtained by reversing the digits. If the difference between the digits is 3, find the number.

Answer 1

Let the face value of the number at ten’s place be x

And the face value of the number at unit’s place be y

Hence, the number is $xy$

Using both fave value and place value we have

Required number = $10\times x+y\times 1$

When the digits are interchanged, the number becomes $yx$

Hence the r eversed number = 10y + x

According to the question,

7(10x + y) = 4(10y + x)

66x = 33y

2x - y = 0...(1)

Also,

From (1) 2(3) - y = 0

y = 6

Thus, Required number = 10(3) + 6 = 36