number riddle, algebra help please!?

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Swaym~

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The sum of the digits of a two-digit number is 7. When the digits are reversed, the number is increased by 27. Find the number :D please
 
xy is the number
x+y = 7
y*10+x = x*10+y + 27
9y = 9x + 27
y = x+3
x = 4
y = 7
the number is 47
reversed number is 74 = 47 + 27
 
Tens (x), unit (y):
x + y = 7
y = 7 - x

10y + x - (10x + y) = 27
10y + x - 10x - y = 27
9y - 9x = 27
y - x = 3
y = x + 3

7 - x = x + 3
2x = 4
x = 2

y = 7 - 2
y = 5

Answer: 25 (many solutions as Henry's 47 also apply).
 
Ok, so lets work this out:
what 2 digits equal 7?

- 5+2
- 3+4 (lets try this one)

Now you must reverse the digits, so:
3+4=7
34 - 7 = 27

Your riddle #'s are: 4 & 3.

Good luck.
 
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