Question

The sum of 2 digit number is 7. if the digit are reversing the new number increased by 3 lrss than 4 times the original number find the original number

Answer 1

This question is from textbook Arithmetic and algebra again

: The sum of the digits of a two-digit number is 7. If the digits are reversed, the new number increased by 3 equals 4 times the original number. Find the original number.

here is what I have done:

original number 10x + y

new number 10y + x

x + y = 7

10x + y = 10y + x + 3

10x -x + y -y = 10y -y + x -x + 3

9x = 9y + 3

x = y + 3

x + y = 7

(y+3) + y = 7

2y + 3 = 7

2y +3 -3 = 7 -3

2y = 4

2y/2 = 4/2

y = 2

x + y = 7

2 + y = 7

2 -2 + y = 7 -2

y = 5

x = 2