Question

David can paint a fence in ten hours. Alex can paint the same fence in eight hours. If

Answer 1

Answer:

40/9

Step-by-step explanation:

Use the work formula, $\frac{1}{A}$ + $\frac{1}{B}$ = $\frac{1}{T}$, where A is the amount of time it takes one person, B is the amount of time it takes another person, and T is the time it takes for them to work together.

Plug in the times for David and Alex alone:

$\frac{1}{10}$ + $\frac{1}{8}$ = $\frac{1}{T}$

Find the least common denominator, which is 40.

$\frac{4}{40}$ + $\frac{5}{40}$ = $\frac{1}{T}$

$\frac{9}{40}$ = $\frac{1}{T}$

Cross multiply and solve for T:

9T = 40

T = 40/9

So, if they worked together, it would take them 40/9 hours

Answer 2

Answer:

40/9

Step-by-step explanation:

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