Question

The sum of the digits of a 2 digits number is 9. Also,nine times, this number is twice the number obtained by reversing the order of the digits. find the number

Answer 1

#x+y=9
#9(10x+y)=2(10y+x)
#Solve it. You'll get the required value of x and y.
#10x+y is the number.
Answer is 18.

Answer 2

x +y =9 .........eq. 1)
9 (10x+y) =2(10y+x)
90x+9y=20y+2x
88x =11y
8x=y
from 1) x+y=9
x+8x =9
x= 1
and y=8.
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