Question

1. If y varies directly as x, and y=30 when x=4, find the constant of proportionality.

2. If y varies inversely as x, and y=2 when x=10, find x when y=4.

3. If a varies jointly as b and c, and a=-10, when b=12 and c=2, find a when b=8 and c=1/2.

Answer 1

1. y=kx plug in your # and solve for k
2. y=k/x solve for k and then plug in your y=4 to find x with the k value you found.
3. I forgot how to do this one.. it's been years lol.

Answer 2

50