Question

the tens digit of a two digit number is 5 greater the units digit. If you subtract double the reversed number from it, the result is a fourth of the original number. Find the original number.

Answer 1

Given:

The tens digit of a two digit number is 5 greater the units digit.

If you subtract double the reversed number from it, the result is a fourth of the original number.

To find:

The original number.

Solution:

Let n be the two digit number and x be the unit digit. Then tens digit is (x+5) and the original number is:

$n=(x+5)\times 10+x\times 1$

$n=10x+50+x$

$n=11x+50$

Reversed number is:

$x\times 10+(x+5)\times 1=10x+x+5$

$x\times 10+(x+5)\times 1=11x+5$

If you subtract double the reversed number from it, the result is a fourth of the original number.

$11x+50-2(11x+5)=\dfrac{1}{4}(11x+50)$

$11x+50-22x-10=\dfrac{1}{4}(11x+50)$

$40-11x=\dfrac{1}{4}(11x+50)$

Multiply both sides by 4.

$160-44x=11x+50$

$160-50=11x+44x$

$110=55x$

Divide both sides by 55.

$\dfrac{110}{55}=x$

$2=x$

The unit digit is 2. So, the tens digit is $2+5=7$.

Therefore, the original number is 72.