Question 551297
t = tens digit , u = units digit


"The value of certain two digit number is four less than six times the sum of it's digits"
___ 10t + u + 4 = 6(t + u)


"If the digits of the number are reversed, the resulting number is nine less than the original number"
___ 10u + t + 9 = 10t + u ___ 9u + 9 = 9t ___ u + 1 = t


substituting ___ 10(u + 1) + u + 4 = 6[(u + 1) + u] ___ 11u + 14 = 12u + 6


solve for u, then substitute back to find t ___ the number is "tu"