A perfect mathematics challenge to tease your brain and check your critical and creative thinking skills!

## Challenge:

Edward can finish \(40\%\) of a job in 2 days and Emanuel can finish \(15\%\) of the same job in 3 days. How many days does it take Edward and Emanuel to finish \(75\%\) of the same job if they work together?

**A-** 2.5

**B-** 3

**C-** 4.5

**D-** 5

**E-** 5.5

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The correct answer is B.

Edward can finish \(40\%\) of a job in 2 days. Therefore, he can finish the job in 5 days.

\(40\%\) of x = 2 → x = 5

Emanuel can finish \(15\%\) of the same job in 3 days. So, he can finish the whole job in 20 days.

\(15\%\) of x = 3 → x = 20

First, let’s find the time it takes to finish the job if both Edward and Emanuel work together.

\(\frac{1}{a} + \frac{1}{b} = \frac{1}{t} → \frac{1}{5} + \frac{1}{20} = \frac{1}{t} →\frac{5}{20} = \frac{1}{t} → t = 4\)

It takes 4 days to finish the job if both of them work together. Therefore, they can finish \(75\%\) of the job in 3 days:

\(x = 4 → 75\%\) of x equals 3.