Let

b = the number of births in thousands

d = the number of deaths in thousands

Each day the number of births in the world is 84 thousand less than three times the number of deaths:

b = 3d - 84

Population increase in a single day is 228 thousand:

b - d = 228

We have the following system of equations:

b = 3d - 84

b - d = 228

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b = 384 thousands births

d = 156 thousands deaths

The number of births per day is 84 thousands births.

The number of deaths per day is 156 thousands deaths.