These operators have the usual precedence in C++: AND before OR.

// You can drive with a foreign license for up to 60 days
bool can_drive = has_domestic_license || has_foreign_license && num_days <= 60;

This code is equivalent to the following:

// You can drive with a foreign license for up to 60 days
bool can_drive = has_domestic_license || (has_foreign_license && num_days <= 60);

Adding the parenthesis does not change the behavior, though, it does make it easier to read. By adding these parentheses, no confusion exist about the intent of the writer.