Since you don’t understand the question, I’ll try to break it down.

It’s asking how many total bricks were laid down, but we don’t known the rate of bricks per hour, or how many hours. This is why you use X and Y.

It’s asking for us to find how many total bricks would have been laid down if we knew X and Y.

The first part of the brick laying is X bricks per Y hours.

The second part is X/2 per 2Y hours

The trick/ way you’ll get the correct answer is by realizing that the rates are equal. The /2 and *2 cancel out.

Imagine it miles per hour. 60mph is the same as 30 miles per .5 hour.

So because it’s asking for the equation for the total bricks laid. Spoiler: it’s just 2XY.

To break it down further, our total for the first part is X (bricks per hour) * Y (total hours). The second part is the same so... Our first rate + second rate. = 2XY

I just barely finished 9th grade, so I could be very wrong XD I don’t think I am, but be careful and double check my answer.