Given AE EC , for what value of x is quadrilateral ABCD a parallelogram? с 3x+1​

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences. they randomly assigned 20 participants to a control group or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training. which statistical analysis should be performed to answer the researchers' question?

The length of a rectangular piece of land is 92 yards more than three times its width. the perimeter is 760 yards. find its dimensions.

Solve the system of equations. y=3x-1 and y=-2x+9. show work