Question

15 men can reap a field in 25 days. In how many days can 20 men reap the same field.​

Answer 1

Answer:

15×25 = x × 20

x = 15×25 / 20

x = 18.75 days

Step-by-step explanation:

Answer 2

Answer:

$\boxed{\sf \: Number \:of \: days\: required\:is\:18\dfrac{3}{4} \: }$

Step-by-step explanation:

Given that, 15 men can reap a field in 25 days.

Now, we have to find how many days can 20 men reap the same field.

We know, less men, more number of days are required.

So, it means, number of men and number of days required are in inverse variation.

Let assume that number of days required be x.

So, we have

$\begin{array}{|c|c|c|} \\ \rm Number \:of\:men \:\: &\rm 15 \: &\rm 20\: \: \\ \\ \rm Number \: of \: days \: &\rm 25&\rm x \\ \end{array}$

So, using law of inverse variation, we have

$\sf \: 15 \times 25 = 20 \times x$

$\sf \:x = \dfrac{ 15 \times 25}{ 20}$

$\sf \:x = \dfrac{ 15 \times 5}{ 4}$

$\sf \:x = \dfrac{75}{4}$

$\qquad\sf\implies \sf \:x = 18\dfrac{3}{4}$

Hence,

$\sf\implies \sf \: Number \:of \: days\: required\:is\:18\dfrac{3}{4}$

$\rule{190pt}{2pt}$

Additional Information

$\begin{gathered}\: \: \: \: \: \: \begin{gathered}\begin{gathered} \footnotesize{\boxed{ \begin{array}{cc} \small\underline{\frak{\pmb{{More \: identities}}}} \\ \\ \bigstar \: \bf{ {(x + y)}^{2} = {x}^{2} + 2xy + {y}^{2} }\:\\ \\ \bigstar \: \bf{ {(x - y)}^{2} = {x}^{2} - 2xy + {y}^{2} }\:\\ \\ \bigstar \: \bf{ {x}^{2} - {y}^{2} = (x + y)(x - y)}\:\\ \\ \bigstar \: \bf{ {(x + y)}^{2} - {(x - y)}^{2} = 4xy}\:\\ \\ \bigstar \: \bf{ {(x + y)}^{2} + {(x - y)}^{2} = 2( {x}^{2} + {y}^{2})}\:\\ \\ \bigstar \: \bf{ {(x + y)}^{3} = {x}^{3} + {y}^{3} + 3xy(x + y)}\:\\ \\ \bigstar \: \bf{ {(x - y)}^{3} = {x}^{3} - {y}^{3} - 3xy(x - y) }\:\\ \\ \bigstar \: \bf{ {x}^{3} + {y}^{3} = (x + y)( {x}^{2} - xy + {y}^{2} )}\: \end{array} }}\end{gathered}\end{gathered}\end{gathered}$