Right-of-way rules help people drive safely. These rules go along with courtesy and common sense. Bicycle riders, moped riders, and pedestrians must follow these rules, too.
Never insist on taking the right-of-way. Note that the law does not allow anyone the right-of-way. It only states who must yield. When a driver is legally required to yield the right-of-way but fails to do so, other drivers are required to stop or yield as necessary for safety. So, if another driver does not yield to you when he or she should, forget it. Let the other driver go first. You will help prevent accidents and make driving more pleasant.
At an intersection without STOP or YIELD signs (uncontrolled intersection), slow down and prepare to stop. Yield to vehicles already in the intersection or entering it in front of you. Always yield to the car that arrived first. If you and another driver reach the intersection at the same time, yield if the car is on your right.
However, do not always insist on others going ahead of you. If another vehicle expects you to take your legal turn, you may delay traffic by stopping or slowing unnecessarily to allow another vehicle to go ahead of you.
At a four-way stop if two vehicles reach the intersection simultaneously, the vehicle on the left must yield the right-of-way to the vehicle on the right.
So, in the given graphic, B should yield to A.
In some places you will find STOP signs on one side of the intersection but no signal control for the cross traffic as shown in the graphic. In this case, you have to remain STOPPED until all cross traffic is gone. So, in the given situation, the white car can not make a left turn until the blue car gets out of its way.
At T-intersections, vehicles on the through road have the right-of-way.