t = tens digit
u = units digit
10t+u = the number
t+u = sum of the digirs

>>...the units digit of a two-digit number 
is 3 less than its tens digit...<<

            

>>...if the number is divided by the sum of 
its digit, the quotient is 6 and the remainder
is 8...<<
                 
               quotient 
sum of digits) the number
               __________
               remainder

  





So we have this system of equations:




Solve that by substitution and we get

t = 7 and u = 4

So the number is 74.

the units digit, 4, is 3 less than its tens digit 7.  That 
checks.

If the number, 74, is divided by the sum of its digit, 11, 
the quotient is 6 and the remainder is 8

    6               
11)74
   66
    8

That checks.

Edwin