Direct, inverse, and joint variation Find k and y when x = 6 and z = 8, if y varies jointly as x and z and y = 60 when z = 3 and x = 4.

a)k = 1/5 , y = 240

b)k = 5 , y = 240

c)k = 1/5 , y = 9.6

d)k = 5 , y = 9.6