Respuesta :

Answer:

y = -240

Step-by-step explanation:

If y varies jointly as x and z, then y/(xz) = k where k is the constant of proportion

60/10(-3) = 60/-30 = -2 = k

Now,  y/(xz) = -2

          y/8(15) = -2

          y/120 = -2

                y = -240