<PRE><B>Question 892314</B>
Set t = the tens digit
    u = the unitis digit
t + u = 9
Solve for t by adding -u to each side.
t = 9 - u
The value of the number is 10t + u.
(10t + u) = 6u
Substitute (9 - u) for t in the above
10(9 - u) + u = 6u
90 - 10u + u = 6u
90 - 9u = 6u
 add 9u to each side
 90 = 15u
divide each side by 15
 6 = u
since t+u = 9
 t + 6 = 9
add -6 to each side
 t = 3
Since t+u = 9, 3+u = 9 and u = 6
So our number is 36
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