Extremely confused, please help me!

Two variables, x and y, vary inversely, and x=12 when y=4. what is the value of y when x=3?

What is the volume of the cone to the nearest cubic millimeter? (use π  = 3.14) a) 46 mm3 b) 128 mm3 c) 183 mm3 d) 275 mm3 diameter = 5 mm height = 7 mm how do you do this problem step by step?

The height above the ground (in feet) of a ball dropped from the top of a 30-foot-tall building after t seconds is given by the polynomial: ? 16t^2+30 what is the height of the ball after 1/2 second?