Question

Q. A number of two digits has the sum of its digits as 7. When 9 is subtracted from the number, digits are reversed. The number is

Answer 1

EXPLANATION.

• GIVEN

a number of two digit has the sum of its digit

as = 7

when 9 is subtracted from the number, digit

are reversed.

TO FIND THE NUMBER.

According to the question,

Let the tens place = x

Let the unit place = y

original number = 10x + y

reversing number = 10y + x

Conditions = 1

A number of two digit has the sum of its

digit = 7

=> x + y = 7 ........(1)

Conditions = 2

when 9 us subtracted from the number, digit

are reversed.

=> 10x + y - 9 = 10y + x

=> 9x - 9y = 9

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

From equation (1) and (2) we get,

=> 2x = 8

=> x = 4

put the value of x = 4 in equation (1)

we get,

=> 4 + y = 7

=> y = 3

Therefore,

Number are = 10x + y

=> 10(4) + 3 = 43

Number are = 43