Where two or more vehicles face stop, slow, warning or caution signs or signals on two or more intersecting cross streets, and are approaching so as to enter the intersection at the same time, where each vehicle is required to stop, the vehicle coming from the right shall have the right-of-way. Where each vehicle is required to slow, the vehicle coming from the right shall have the right-of-way. When each vehicle is required to take caution, the vehicle coming from the right shall have the right-of-way. When one vehicle is required to stop and the ether to slow or take caution, the one slowing or taking caution shall have the right-of-way. When one vehicle is required to slow and the other to take caution, the one required to take caution shall have the right-of-way. In any event, a vehicle which has already entered the intersection shall have the right-of-way over one which has not so entered the intersection.
(47 O.S. § 11-403(d)) (`90 Code, § 20-69)