Can someone help me in kinda dumb

Determine the number of girls in a math class with 87 boys if there are 25 girls for every 75 boys

Is a positive integer raised to a negative power always positive

A3-dimensional figure has a square base and 4 lateral faces that meet at a point. explain the difference between the cross sections when a slice is made perpendicular to the base through the vertex, and when a slice is made perpendicular to the base and not through the vertex