Answer:

B. -24

Step-by-step explanation:

x varies jointly as y and z

x = kyz where k is the constant of variation

if x = 9, y = 2 and z = -3

x = kyz

9 = k ( 2 ) ( -3 )

9 = k ( -6 )

k = -9/6

k = -3/2

if y = 4 and z = 4, find x.

x = kyz

x = ( -3/2 ) ( 4 ) ( 4 )

x = -24 B.