What is the value of z for the equation

1) -3
2) -7
3) 3
4) 7​

0if x and y vary inversely and y=6 as x=7, what is the constant of variation?

Find the equation of the ellipse with the following properties. the ellipse with foci at (0, 6) and (0, -6); y-intercepts (0, 8) and (0, -8).edit: the answer is x^2 over 28 + y^2 over 64 = 1

Study results indicate that the mean length of time people spend on a bus in a city is between 21.2 min and 24.5 min what is the study margin of the error?