It takes 12 people 15 hours to complete and certain job. how many hours would it take 18 people, working at the same rate to complete 2/5 of the same job?

2 Hours

Step-by-step explanation:

Required man hours to complete the full job = 12 *15

                                                                           =180 Man hours

Required man hours to complete the 2/5 of the job = 180/5

                                                                                      = 36 Man hours

if 18 peoples are working,

required hours to complete the 2/5 of the job = 36 /18

                                                                            = 2 hours

x = -4

step-by-step explanation:

- 20 - 4(x + 3) = 4x

=> -20 - 4x - 12 = 4x

=> - 32 -4x = 4x

=> -32 = 4x + 4x

=> - 32 = 8x

=> -32/8 = x

=> -4 = x