Andrew M. answered • 01/30/18

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Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors

Note the value of a two digit number xy is 10x + y

23 = 2(10) + 3

Let the 2 digit number be xy

The units digit of a two-digit number is one more than twice the tens digit:

y = 2x + 1

reversed, the new number is 2 more than twice the original number:

10y + x = 2(10x + y) + 2

10y + x = 20x + 2y + 2

8y - 19x = 2

Since y=2x+1, substitute that in and solve for x

8(2x+ 1) - 19x = 2

16x + 8 - 19x = 2

-3x = -6

x = 2

y = 2x+1 = 5

The original number xy = 25