When two vehicles approach or enter an intersection from different roadways at approximately the same time, the driver of the vehicle on the left must yield the right-of-way to the vehicle on the right. This rule may be modified at through highways or streets and where otherwise inconsistent with the provisions of this traffic code.
(ILCS Ch. 625, Act 5, § 11-901) (1999 Code, § 71.060) Penalty, see § 71.999