Answer: she baked 1225 muffins.
Explanation:
Let x represent the number of muffins that she baked.
She gave 4/11 of the muffins to her friends. This means that the number of muffins that she gave to her friends is 4x/11. The number of muffins remaining is
x - 4x/7 = 3x/7
She gave 4/7 of the remainder to the guests at the event. This means that the number of muffins that she gave to the guests at the event is
4/7 × 3x/7 = 12x/49
The number of muffins remaining would be
3x/7 - 12x/49 = 9x/49
She had 225 muffins left. It means that
9x/49 = 225
9x = 225 × 49 = 11025
x = 11025/9
x = 1225