Sam have 10 books and mary have 10 books too how manny books they all have

Which formula finds the probability that a point on the grid below will be in the blue area? p(blue) = total number of squares number of blue squares number of blue squares p(blue) = total number of squares number of blue squares p(blue) = number of white squares

The figure below shows rectangle abcd and the triangle eca on a coordinate plane. which of the following expressions represents the perimeter of triangle of triangle eca in units

Precalculus question, image attached.