Question

A pencil costs Rs 5 more than an eraser. The total cost of 5 pencils and 10 erasers is Rs 100. What is the cost of a single pencil and a single eraser?

• A. Eraser - Rs 15
  Pencil - Rs 20
• B. Eraser - Rs 10
  Pencil - Rs 15
• C. Eraser - Rs 5
  Pencil - Rs 10
• D. None of the above

Answer 1

The correct option is C Eraser - Rs 5

Pencil - Rs 10
Let the cost of an eraser be $x$
Cost of pencil = $x+5$.
Now, the cost of 5 pencils will be $5\times (x+5)=5(x+5)$
The cost of 10 erasers will be $10\times x=10x$
$5(x+5)+10x=100$
$5x+25+10x=100$
$15x=100-25=75$
$x=\frac{75}{15}=5$
The cost of an eraser is $Rs5$
The cost of a pencil is $x+5=5+5=Rs10$