A shoe store bought a pair of shoes for $50, and sold it for $80. What percentage was the mark-up?

Solve 2x+y=3 x+y=5 in substitution method

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?

Ling listed all of the factors of a mystery number: 1,2,4,8,16,32 what is the mystery number?