For this case we define the following variable:
x: time it takes A to perform the job separately.
We then have the following equation:
[tex] \frac{1}{x} + \frac{1}{2x} = \frac{1}{4} [/tex]
From here, we clear the value of x.
We have then:
[tex] \frac{4x}{x} + \frac{4x}{2x} = \frac{4x}{4} [/tex]
[tex] 4 + 2 = x [/tex]
[tex] x = 6 [/tex]
Therefore, the time it takes for B to complete the work is:
[tex] 2x = 2 (6) = 12 [/tex]
Answer:
B will spend 12 hours doing that work separately
