Question

A man purchased 147 stamp of 60-paisa and 35 paisa. the total amount he spent was rs. 68.20. how many 35-paisa stamps were purchased by him?

Answer 1

Let no. of stamps of 60p be x, and that of 35p be y,

So we have

x + y = 147....(1)

0.60 x + 0.35 y = 68.20....(2)

Solving (1) and (2) we get

x = 147 - y

Putting this in (2) we get

0.6(147 - y) + 0.35y = 68.20

88.20 - 0.6y + 0.35y = 68.20

88.20 - 0.25y = 68.20

0.25y = 20

y = 20÷0.25

y = 80

Therefore 80 stamps of 35 paise were purchased.

Answer 2

Let the number of 60p stamps be x and the number of 35p stamps be y.

Thus,

x + y = 147  -> Eqn i

0.60x + 0.35y = 68.20 -> Eqn ii

From Eqn i, x = 147 – y

Substituting the above value of x in Eqn ii,

0.60(147 - y) +0.35y = 68.20

=> 88.20 – 0.60y + 0.35y = 68.20

=> 88.20 - 0.25y = 68.20

=> -0.25y = -20

=> 0.25y = 20

=> y = 80

Thus, number of 35p stamps = y = 80.