Too many uses of "digit"....
Five times the sum of the digits of a two-digit number is 13 less than the original number. If you reverse the digits in the two-digit number, four times the sum of its two digits is 21 less than the reversed two-digit number?
I'll solve that problem for you, but only if you give me some money.
This link will help you.
5(x + y) = 10x+y - 13.......(1)
4(x + y) = 10y+x - 21.........(2)
After solving it you will get the value of x=9 and y=8
For checking put the values in the equations
4(9 + 8) = 80+9 - 21
4(17) = 89-21
68 = 68
I hope it'll help.