Question

The sum of digits of a 2 digit no is 7.if digits are reversed the new number decreases by twice the original number.Find the number

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Answer 1

Answer:

25

Step-by-step explanation:

let the digits be x and y... and so, the original number be 10x + y ( since x in tenth place and y in unit place)

so, given : sum of the digits = x + y = 7 ---------> (A)

reversing the digits means y in tenth place and x in unit place.. so, the reversed number be 10y + x

given: reversed number is decreased by 2 = twice original number

so, 10y + x - 2 = 2(10x + y)

simplifying : 19x - 8y = -2 ------------> (B)

solving 2 eqns (A) & (B) ,

we get x = 2 and y = 5

so the original number is 10x + y = 10(2) + 5 = 25

& the reversed number is 10y + x = 10(5) + 2 = 52

& the reversed number 52 when decreased by 2 is 50 which is twice the original number 25

Ans: the original number is 25