Answer: 12 hours
Step-by-step explanation:
Given : Working together, it takes Sam, Jenna, and Francisco two hours to paint one room.
When Sam works alone, he can paint one room in 6 hours. When Jenna works alone, she can paint one room in 4 hours.
Let 't' be the time taken by Francisco to paint one room on his own.
Then , we have
Rate of work of Sam +Rate of work of Jenna + Rate of work of Francisco =Rate of work they all do together

i.e. 
i.e. 
i.e. 
i.e. 
i.e. 
i.e. 
i.e. t= 12
Hence, Francisco would take 12 hours to paint one room on his own.
The value of a=9,b=3 and c=1
Step-by-step explanation:
The graph shown is for function f(x)
The given function is f(x)=
Table says,
X Y
-2 a
1 b
0 c
1 (1/3)
2 (1/9)
To find value of a:
From table, for output value a, input value, x=(-2)
we can write f(-2)=a
Therefore,
f(x)=
f(-2)=
a=
a=
a=9
To find value of b:
From table, for output value a, input value, x=(-1)
we can write f(-1)=b
Therefore,
f(x)=
f(-1)=
b=
b=
b=3
To find value of c:
From table, for output value a, input value, x=(0)
we can write f(0)=c
Therefore,
f(x)=
f(0)=
c=
c=1