250, and this is because of probability. Since half of the numbers are odd numbers, and half are even. It would be hard to determine, your probability would be 1/2. 1/2 of 500 is going to be 250.
setup a simple algebraic equation and solve.
5x = 7x-28
-5x -5x
0=2x-28
+28 +28
28=2x
Now divide both sides by 2 and you get that she is 14
3√10^4x is equivalent to -√10 3/4^x and -4√10^3x they are all equivalent