Schools should really vet the papers before releasing.  Sweets can become cookies… 

If I follow the question exactly, the answer would be ZERO cos he only has sweets!!  lol  I wonder if any kid gave this as an answer…kekeke

                 Peter                                    Nicole

Before       4u    x 4 = 16u                      9u

Ate            -240  x 4 = -960                 -99

After           p x 4 = 4p                            4p

16u-960 = 9u-99

7u = 861

u = 123

Therefore, no of sweets Peter has at first = 4u =  4×123 = 492