Question

Sathish went to the market with Rs. 200. If he buys three pens and six pencils he uses up all his money. On the other hand if he buys three pencils and six pens he would fall short by 20%. If he wants to buy equal number of pens & pencils, how many pencils can he buy?

Answer 1

you can do like the above method.....

Answer 2

Let Cost of one pen = Rs x

And Cost of one Pencil = Rs y

        →  Total Amount of money possessed by sathish when he went to market= Rs 200

Amount used when sathish buys three pens and six pencils = Rs 200

Amount used when Sathish buys three pencils and six pens= Rs 200 + 20% of 200= 200 +[$\frac{20\times200}{100} = 20\times2=40$ ]= Rs 240

Writing the statement in terms of equation

3 x + 6 y = 200 -----(1)

6 x + 3 y = 240-------(2)

→2 × Equation (1)  -  Equation (2)= 400 - 240

→ 9 y = 400 - 240

→y = $\frac{160}{9}$

Substituting the value of y in 2, we get

6 x + $\frac{480}{9}$ = 240

6 x = $240 -\frac{480}{9}=\frac{2160 -480}{9}=\frac{1680}{9}$

x = $\frac{280}{9}$

As Sathish wants to buy equal number of pen and pencil.

In that case , x=y

→$\frac{280y}{9} +\frac{160 y}{9}= 200\\\frac{440 y}{9}=200\\y=\frac{200\times9}{440}=\frac{45}{11}$

So, number of pencils that Sathish can buy if he buys equal number of pens & pencils = $\frac{45}{11}=   4 pencils (Approx)$