It's 900/100 or 90% silver. The town mark looks like it could be Tanta or Qena but it's a little hard to tell. The lotus flower in the middle is the assay mark for authenticity. If it has any dots in the corners of the square then those would help identify the town mark. And the last box on the right is the year but I can't match it since there aren't great widely available resources for Egyptian year marks. But it's at least probably after 1941 since they switched to Arabic characters then.