Question

sum of 2 digits of a two digit number is 9.

solve question 2

Answer 1

Answer: 18

Step-by-step explanation:

Let the 2-digit number be XY

Its represented as 10X + Y

Given,

Sum of digits = 9

X+Y = 9 ....(i)

Then, 9 times the number = twice the number obtained by reversing its digits

9 [10X + Y] = 2 [10Y + X]

90X + 9Y = 20Y + 2X

88X - 11Y = 0

8X - Y = 0           [Dividing throughout by '11']

Y = 8X ....(ii)

Substitute the value of 'Y' in eq.(i)

X + 8X = 9

9X = 9

X = 1

Y = 8X = 8*1 = 8

Hence the number is 18.

Answer 2

REFER TO ATTACHED STATEMENT