The sum of (a + b) + c is equal to the sum of a + (b + c) as explained by the blank

Aline on the wall and a line on the floor are skew. always, sometimes, or never?

(mc 02.03) what set of reflections and rotations would carry rectangle abcd onto itself? reflect over the y-axis, reflect over the x-axis, rotate 180° rotate 180°, reflect over the x-axis, reflect over the line y=x reflect over the x-axis, rotate 180°, reflect over the x-axis rotate 180, reflect over the y-axis, reflect over the line y=x

The two square pyramids are similar. find the total volume of both pyramids if the ratio of their surface areas is 9/16