SOLUTION: The last digit is the double of the first digit The second and third digit are same Third and fourth digit make the number which is twice the number in the first and second digi

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Question 976750: The last digit is the double of the first digit
The second and third digit are same
Third and fourth digit make the number which is twice
the number in the first and second digit and it would be a number plate

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Four digits a, b, c, d
:
Write an equation for each statement:
The last digit is the double of the first digit.
d = 2a
The second and third digit are same.
b = c
Third and fourth digit make the number which is twice the number in the first and second digit.
10c + d = 2(10a + b)
10c + d = 20a + 2b
Replace b with c, replace d with 2a
10c + 2a = 20a + 2c
10c - 2c = 20a - 2a
8c = 18a
4c = 9a
c = 9%2F4a
only one single digit integer solution to this
a = 4, then c = 9
therefore
b = 9
and
d = 2(4) = 8
:
and it would be a number plate: 4998
:
:
We can confirm this in the last statement: 98 = 2(49)