Answer:
B
Step-by-step explanation:
6 machines complete the job in 12 days;
the more machine you have faster the job will be done, inverse proportion
6 machines --- 12 days
x machines -- 8 days
you reduce the number of days by a factor of 1.5 (12/1.5)
sou you hvae to increase the number of machines by 1.5
6 x 1.5 = 9, so you will need 3 additional machines