Answer:
D(x) = 3x
Step-by-step explanation:
Micah travels at a rate of 'x' feet over a specific period.
Linda travels at a rate of '2x' feet over that same period.
Since they are walking in opposite directions, the total distance they have walked towards one another (D) can be determined by adding both distances:
[tex]D(x) = x+2x\\D(x) = 3x[/tex]
The expression that describes the number of feet they have walked toward one another is D(x) = 3x.