What number must be added to the expression below to complete the square? х2 - 20х

Which solid has two triangular bases and three lateral faces, each in the shape of a rectangle? triangular prism triangular pyramid rectangular prism rectangular pyramid

Mrs. morton has a special reward system for her class. when all her students behave well, she rewards them by putting 3 marbles into a marble jar. when the jar has 100 or more marbles, the students have a party. right now, the the jar has 24 marbles. how could mrs. morton reward the class in order for the students to have a party?

The areas of two similar triangles are 72dm2 and 50dm2. the sum of their perimeters is 226dm. what is the perimeter of each of these triangles?