If the order will matter, then (I think) the probability would be 1/12.
If the order does not matter, then (I think) the probability would be 1/72.
There are 9000 four-digit natural numbers, of which (9000 : 2 =) 4500 are odd.
A = 4500
There are (9000 : 3 =) 3000 four-digit natural numbers that are multiples of 3.
B = 3000
Hence 4500 + 3000 = 7500.
I'm not sure: 4/5
a + b + c = 60
\(7-9x=11 \mbox{ }| -7 \\ -9x=4 \mbox{ }| :(-9) \\ \frac{-9x}{-9} = \frac{4}{-9} \\ x = \frac{4}{-9} \mbox{ }| \cdot (-1) \\ x = \frac{-4}{9} = -0.\overline4\)
f = 268/5
Since the two equations have a +, they are commutative and can be, for example, x = 2, y = 4 and x = 4, y = 2.
\((x, \mbox{ } y) = (4, \mbox{ } 6)\), \((x, \mbox{ } y) = (6, \mbox{ } 4)\) are the only possible values of x and y.
I'm not sure, but I think that b + c = 48.
Guest is right.
Sorry, that this took long.
\(2 + 2\sqrt{2}, \mbox{ } 2 - 2\sqrt{2}\) .
