Question

a man sold a watch at a loss of 10%.If he taken rs.70 more,there would have been a gain of 4%. Find the cost price of that watch?

Answer 1

selling price = x
loss = 10%
Let the cost price = y

$\frac{y-x}{y} = \frac{10}{100}$

⇒$\frac{y-x}{y} = 0.1$

⇒$y-x = 0.1y$
⇒$y-0.1y = x$
⇒$x = 0.9y$

If he had taken Rs. 70 more,
selling price would be = x+70
gain =4%

$\frac{(x+70)-y}{y} = \frac{4}{100}$
⇒$x+70-y = 0.04y$
⇒$0.9y + 70 - y = 0.04y$
⇒$0.9y -y -0.04y = -70$
⇒ [tex ]-0.14y = -70 [ /tex]
⇒$y = (-70)/(-0.14)$
⇒ y = 500 <<<<<cost price