She can travel 3000 miles
The degree of vertex b is b
The probability is 8 out of 20 or 40 percent
For this case we have the following equation:

We must clear the value of the variable "x" as a function of r, s and t:
If we multiply by "r" on both sides of the equation we have:

If we subtract "t" on both sides of the equation we have:

If we divide by "2" on both sides of the equation we have:

Thus, the value of the variable "x" is:

Answer:
