Question

four rulers and three pencils cost £2.15 and three rulers and four pencils cost £2.05 what is the cost of a pencil

Answer 1

Answer:

Cost of pencil is £0.30835

Step-by-step explanation

Let the cost of a ruler is x

Let the cost of a pencil is y

Given that four rulers and three pencils cost £2.15

⇒4x + 3y = 2.15 → (1)

Given that three rulers and four pencils cost £2.05

⇒3x + 4y = 2.05 → (2)

Equation (1) $\times$ 4⇒ 16x + 12y = 8.60 → (3)

Equation (2) $\times$ 3⇒ 9x + 12y = 6.15 → (4)

(3) - (4) ⇒ 7x = 2.45

                 x = 0.2722

Therefore cost of pencil, y = $\frac{2.05-\left[3\times 0.2722\right]}{4}=0.30835$   (from equation (2))