SOLUTION: The tens digit of a two-digit number is 1 more than three times the units digit. If the sum of the digits is 9, find the number.

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Question 1061157: The tens digit of a two-digit number is 1 more than three times the units digit. If the sum of the digits is 9, find the number.
Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!
Tens digit is 'a'
Ones digit is 'b'
++a+=+3%2Ab%2B1++ (1)
++a%2Bb+=+9++++++ (2)

Substitute right hand side of (1) for 'a' in (2):
++%283%2Ab%2B1+%2B+b%29+=+9+
+++4b+%2B+1+=+9+
++++4b+=+8+
++++b+=+2+ —from eq(1)—> +a=7+
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Ans: The number is 72
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Check (using eq(2)): 3*2+1 = 7 (ok)