Question 857384
The difference of the digits of a 2-digit number is 5. If the digits are reversed, the new number is 7 greater than twice the original number. What is the units digit of the original number.
***
let u=units digit
let t=tens digit
u-t=5
u=t+5
..
10u+t=2(10t+u)+7
10(t+5)+t=20t+2u+7
10(t+5)+t=20t+2(t+5)+7
10t+50+t=20t+2t+10+7
11t=33
t=3
u=t+5=8
units digit of the original number=8