The total cost of 12 pens and 5 pencils is equal to ₹ 111. Also, the cost of 1 pencil is ₹ 5 less than the cost of 1 pen. What is the cost of 8 pens and 9 pencils?

• a)Rs 89
• b)Rs 91
• c)Rs 97
• d)Rs 98

Let’s solve this step-by-step to find the cost of 8 pens and 9 pencils:

1. Define variables:
   • Let x be the cost of 1 pen.
   • Since the cost of 1 pencil is ₹ 5 less than the cost of 1 pen, the cost of 1 pencil is (x – 5).
2. Set up the equation based on the given information:
   • The total cost of 12 pens is 12x.
   • The total cost of 5 pencils is 5(x – 5).
   • The total cost of 12 pens and 5 pencils is ₹ 111.
3. Translate the information into an equation: 12x + 5(x – 5) = 111
4. Solve the equation:
   • Expand the equation: 12x + 5x – 25 = 111
   • Combine like terms: 17x – 25 = 111
   • Add 25 to both sides: 17x = 136
   • Divide both sides by 17: x = 8
5. Find the cost of 1 pencil:
   • Cost of 1 pencil = x – 5 = 8 – 5 = ₹ 3
6. Calculate the cost of 8 pens and 9 pencils:
   • Cost of 8 pens = 8 x ₹ 8 = ₹ 64
   • Cost of 9 pencils = 9 x ₹ 3 = ₹ 27
7. Total cost:
   • Total cost = ₹ 64 (pens) + ₹ 27 (pencils) = ₹ 91

Therefore, the cost of 8 pens and 9 pencils is ₹ 91.