ali1518
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David can paint a fence in ten hours. Alex can paint the same fence in eight hours. If
they worked together how long would it take them?
1/10
1/8
9/40
40/9

Respuesta :

rococo908

Answer:

40/9

Step-by-step explanation:

Use the work formula, [tex]\frac{1}{A}[/tex] + [tex]\frac{1}{B}[/tex] = [tex]\frac{1}{T}[/tex], 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:

[tex]\frac{1}{10}[/tex] + [tex]\frac{1}{8}[/tex] = [tex]\frac{1}{T}[/tex]

Find the least common denominator, which is 40.

[tex]\frac{4}{40}[/tex] + [tex]\frac{5}{40}[/tex] = [tex]\frac{1}{T}[/tex]

[tex]\frac{9}{40}[/tex] = [tex]\frac{1}{T}[/tex]

Cross multiply and solve for T:

9T = 40

T = 40/9

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

Answer:

40/9

Step-by-step explanation:

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