Question 571275
The sum of the digits of a two-digit number greater than 50 is 12. The difference between the digits is 4. Find the two-digit number."
**
let u=units digit
let t=tens digit
t+u=12
t-u=4
add
2t=16
2t=16
t=8
u=12-t=4  
two digit number: 84