Question

Four chairs and two tables cost £218.

Six chairs and seven tables cost £587.

Find the total cost of buying twenty chairs and five tables.

Answer 1

x = cost of a chair = £22

y = cost of a table = £65

£765

Explanation:

Let

x = cost of a chair

y = cost of a table

4x + 2y = 218 (1)

6x + 7y = 587 (2)

Multiply (1) by 6 and (2) by 4

24x + 12y = 1,308 (3)

24x + 28y = 2,348 (4)

Subtract (3) from (4) to eliminate x

28y - 12y = 2,348 - 1,308

16y = 1,040

y = 1,040/16

y = 65

Substitute y = 65 into (1)

4x + 2y = 218 (1)

4x + 2(65) = 218

4x + 130 = 218

4x = 218 - 130

4x = 88

x = 88/4

x = 22

x = cost of a chair = £22

y = cost of a table = £65

Find the total cost of buying twenty chairs and five tables

20x + 5y

Substitute the values of x and y

20x + 5y

= 20(22) + 5(65)

= 440 + 325

= £765