Respuesta :

Answer:

56

Step-by-step explanation:

z varies jointly with x and y:

z = kxy

When x = 2 and y = 2, z = 7.

7 = k(2)(2)

k = 7/4

z = 7/4 xy

When x = 4 and y = 8:

z = 7/4 (4)(8)

z = 56