Answer:
Step-by-step explanation:
If D can paint the room in 6 hours, in 1 hour she gets [tex]\frac{1}{6}[/tex] of the room painted;
If C can paint the room in x hours, in 1 hour she gets [tex]\frac{1}{x}[/tex] of the room painted.
It takes 4 hours to paint it together. Setting up the classic work equation gives us
[tex]\frac{1}{6}+\frac{1}{x}=\frac{1}{4}[/tex] and we need to solve for x. Multiply everything through by the LCM which is 12x:
[tex]12x(\frac{1}{6}+\frac{1}{x}=\frac{1}{4})[/tex] making our equation simplify to
2x + 12 = 3x and solve for x:
12 = x
C can paint the room alone in 12 hours.
