London is standing in a stadium and has the option of running up a staircase or down a staircase for exercise. The function f
(
x
)
=
1
25
(
∣
6
x
∣
+
4
x
)
f(x)=
25
1

(∣6x∣+4x) will determine how many calories London will burn if she runs up
x
x steps. Use a negative value for
x
x if she runs down the stairs. Find and interpret the given function values and determine an appropriate domain for the function.