A simple addition operation can get the answer. The date is delayed by 4 days, that is, it is increased by 4 days on the basis of the original date.
Therefore, it can be concluded that the original competition was 1 11+4 = 15, so the competition was postponed to15.
Extended data:
Vector subtraction:
1, vector subtraction in plane coordinate system:
Vector a=(x 1, y 1), vector (x2, y2),
Vector c= vector a- vector b,
c=(x 1-x2,y 1-y2).
2. Vector subtraction in space coordinate system:
Vector a=(x 1, y 1, z 1), vector (x2, y2, z2),
Vector c= vector a- vector b,
c=(x 1-x2,y 1-y2,z 1-z2).
Baidu encyclopedia-subtraction