5 pens and 6 pencils together cost Rs 9 and 3 pens and 2 pencils cost

1.	5 pens and 6 pencils together cost Rs 9 and 3 pens and 2 pencils cost Rs 5. Find the cost of 1 pen and 1 pencil.
Answer» Let the cost of 1 pen be ‘a’ and the cost of 1 pencil be ‘b’. Given, 5 pens and 6 pencils together cost Rs 9. 5a + 6b = 9 --------- (1) Given, 3 pens and 2 pencils cost Rs 5. 3a + 2b = 5 -------- (2) Multiplying eq2 by 3 and subtracting eq1 from it. 3(3a + 2b) - (5a + 6b ) = 5(3) - 9 ⇒ 9a + 6b – 5a – 6b = 15 – 9 ⇒ 4a = 6 ⇒ a = 3/2 Substituting value of 'a' in (1) ⇒ 15/2 + 6b = 9 ⇒ 6b = 3/2 ⇒ b = 1/4

5 pens and 6 pencils together cost Rs 9 and 3 pens and 2 pencils cost Rs 5. Find the cost of 1 pen and 1 pencil.

Answer»

Let the cost of 1 pen be ‘a’ and the cost of 1 pencil be ‘b’.

Given,

5 pens and 6 pencils together cost Rs 9.

5a + 6b = 9 --------- (1)

Given,

3 pens and 2 pencils cost Rs 5.

3a + 2b = 5 -------- (2)

Multiplying eq2 by 3 and subtracting eq1 from it.

3(3a + 2b) - (5a + 6b ) = 5(3) - 9

⇒ 9a + 6b – 5a – 6b = 15 – 9

⇒ 4a = 6

⇒ a = 3/2

Substituting value of 'a' in (1)

⇒ 15/2 + 6b = 9

⇒ 6b = 3/2

⇒ b = 1/4