The placement of the washer and dryer can vary depending on personal preference and the specific layout of your laundry area. There is no fixed rule stating that the washer must go on the left or the right.
However, it is common practice to install the washing machine on the left side and the dryer on the right. This configuration is often followed because of the typical orientation of laundry room plumbing and venting connections. In many homes, the water supply and drain lines are positioned on the left side, making it more convenient to connect the washer. The dryer, on the other hand, usually requires a vent for hot air exhaust, which is often located on the back or right side of the appliance.
That being said, it's important to consider the specific requirements of your washer and dryer, as well as the available space and accessibility of plumbing and electrical connections in your laundry area. Be sure to follow the manufacturer's guidelines and consult any installation instructions provided with your appliances to determine the best placement for your specific models.