Question

Robbie pays $10.80 when he buys 3 notebooks and 4 pencils. Paniz pays $14.50 when she buys 5 notebooks and 2 pencils. Write down simultaneous equations and use them to find the cost of a notebook, and the cost of a pencil.

Answer 1

Given: Robbie pays $10.80 when he buys 3 notebooks and 4 pencils. Paniz pays $14.50 when she buys 5 notebooks and 2 pencils.

To find: Cost of a notebook and pencil

Explanation: Let the cost of a notebook be x and cost of a pencil be p.

For Robbie who buys 3 notebooks and 4 pencils, the equation is:

3x+4p = 10.80

For Paniz who buys 5 notebooks and 2 pencils, the equation is:

5x+2p = 14.50

Doubling the equation,we get:

10x +4p = 29

Subtracting both equations:

7x= 18.2

=> x= 2.6

Using value of x in equation (i),

7.8+4y = 10.8

=>4y = 3

=> p= 0.75

Therefore, the cost of a notebook is $2.6 and cost of a pencil is $0.75.