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The cost of a set of books is twice the cost of biros. The cost of a set of biros is three times the cost of a set of pencils. Find the cost of a set of biros if 4000 naira is used in buying the three sets of items.

Respuesta :

Answer:

cost of a set of biros = 1200 naira

Step-by-step explanation:

let the cost of a set of books = x

let the cost of a set of biros = y

let the cost of a set of pencils = z

according to the question:

x + y + z = 4000               (1)

x = 2y                                (2)

y = 3z                                (3)

substituting the value of x from equation (2) in (1)

2y + y + z = 4000

3y = 4000 - z              (4)

from equation (3)

z = y/3

by substituting the value of z from equation (3) into (4)

3y = 4000 - y/3

3y = 12000 - y / 3

9y = 12000 - y

9y + y = 12000

10y = 12000

y = 12000/10 = 1200

thus,

cost of a set of biros = 1200 naira