Question

the sum of 2 digit number is 10 and the number is 16 times the unit digit

Answer 1

Let the tens place digit and unit place digits be a and b respectively

According to question 

First condition

a + b = 10  --------(1)

Second condition

10a + b = 16b

=> 10a = 15b

=> a = 3b/2 ---------(2)

Substitute the value of a in equation 1

=> 3b/2 + b = 10

=> 5b / 2 = 10

=> b = 4

a = 6

Required number = 64

Answer 2

let the no be 10a+b
so a+b= 10........i
and
10a+b=16b
10a=15b
2a=3b.......ii
on solving both
a=6. and. b=4

so the 2 digit no (10a+b)=64