Books cost $0.50 and pamphlets cost $0.15 at the book sale. If Mr. Jones spent $90 and purchase 15 more pamphlets than he did books, how many pamphlets did he buy?​

Which is the equation of an ellipse with directrices at x = ±4 and foci at (2, 0) and (−2, 0)?

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%

It is given that the quadratic equation hx²-3x+k=0, where h and k are constants, has roots [tex] \beta \: and \: 2 \beta [/tex]express h in terms of k