Answer:
40,000 workers
Step-by-step explanation:
This question deals with simple rates proportion.
If it takes 20 years for X workers to complete a job,
if we double the amount of workers, we will take half the time.
hence to halve the time from 20 years to 10 years, we will need to double the amount of workers.
In this case we will need 20,000 workers x 2 = 40,000 workers
X + y = 40.....multiply by -4
4x + 6y = 180
-------------------
-4x - 4y = -160 (result of multiplying by -4)
4x + 6y = 180
------------------add
2y = 20
y = 20/2
y = 10 <===
x = 30
Try C but im not 100% sure though
This is an exam! You are not supposed too cheat!
>:O
