For each part of the trip (biking and walking), write an expression for the distance using distance = rate × time.

Add the biking distance and walking distance, and set this sum equal to 36 miles. This will give you an equation in terms of $x$.

Once you have the equation, simplify it step by step: first combine constants, then isolate the $x$ term, and finally divide to find $x$.

In Desmos, type y = 12x + 12 to represent the total distance traveled as a function of biking time $x$.

Add another line: y = 36 to represent the given total distance.

Look at the point where the line y = 12x + 12 intersects the line y = 36. The x-coordinate of this intersection is the value of $x$ that satisfies the problem.

Use the formula distance = rate × time.

• Biking: Jordan rides at 12 miles per hour for $x$ hours, so the biking distance is $12x$ miles.
• Walking: He walks at 4 miles per hour for 3 hours, so the walking distance is $4 \times 3 = 12$ miles.

The total distance is the sum of the biking distance and the walking distance, and we are told this total is 36 miles.

So we write:

Subtract 12 from both sides to get the term with $x$ alone on one side:

Now divide both sides by 12 to solve for $x$:

So, Jordan rode his bike for $\boxed{2}$ hours.