Section 1140. Vehicle approaching or entering intersection

(a) The driver
  of a vehicle approaching an intersection shall yield the right of way to
  a vehicle which has entered the intersection from a different highway.
    (b) When two vehicles enter an intersection from different highways at
  approximately the same time the driver of the vehicle on the left  shall
  yield the right of way to the vehicle on the right.
    (c)  The  right  of  way rules declared in subsections (a) and (b) are
  modified at through highways and otherwise as stated in this title.