3. How many square meters are enclosed in
the track?

For the rectangular shape we have:

And the total area would be:

Replacing we got:

Step-by-step explanation:

For this case using the figure attached we can separate the total area in 3 parts.

For this case and represent the area for a semicircle and the A2 represent the area for a rectangular figure.

We can find the individual areas like this:

For the rectangular shape we have:

And the total area would be:

Replacing we got:

step-by-step explanation:

we are given

since, we have to isolate x on anyone side

so, we can move all x terms on one side

subtract both sides by 2x

add both sides by 9

divide both sides by 4

we get