Question

In a two-digit number, the one's digit is 3times the ten's digit. If 10 is added to the 2 times of the number, its digits interchange their places in the new number. Find the number.

Answer 1

let the digit at tens place be x
and that of ones be y
y=3x..........(given)
3x-y=0............................(1)
BY THE GIVEN CONDITION
2(10x+y)+10=10y+x
20x+2y+10=10y+x
20x-x+2y-10y=-10
19x-8y=-10............................(2)
multiplying eq(1) by 8
24x-8y=0...................(3)
subtracting eq(3)from(2)
-5x=-10
5x=10
x=10/5
x=2
substitute x=2 in eq(1)
3x-y=0
3(2)-y=0
y=6
REQUIRED NUMBER:
10x+y=10(2)+6
=20+6
=26