The sum of four consecutive integers is 1290. The greatest of them is?

Let the 1st number be x

So, the numbers are x, x+1, x+2, x+3 

According to the question:

x + x+1 + x+2 + x+3 = 1290

4x + 6 = 1290

4x = 1284

x = 321

The greatest number is x + 3. So, the greatest number is 321 + 3 = 324