Answer:
3.75 hours
Step-by-step explanation:
Total time needed
5 * 6 = 30 hours
with 8 people
30/8 = 3.75 hours
(20+x)*2=x-6
40+2x=x-6
40=-x-6
46=-x
check:
x=-46
20-46*2=-46-6
-26*2=-52
-52=-52
1/2
1/2=10/20