-1/105:(-1/107)

107/105

Brief steps:

• A:B = A/B
• (-1/105) : (-1/107) = (-1/105) ÷ (-1/107) = (-1/105) × (-107/1) = 107/105
• 107/105 = 1 2/105 (simplest improper fraction is 107/105).