Question

3 kg of potatoes and 4 kg of carrots have a total cost of 440p.

4 kg of potatoes and 3 kg of carrots have a total cost of 470p.
Work out the total cost of 1 kg of potatoes and 1 kg of carrots.

Answer 1

Potatoes cost 80p / kg and carrots 50p/kg.

Explanation:

3p + 4c = 440

4p + 3c = 470 (where p = cost 1kg of potatoes and c is same of carrots).

Multiply the first equation by -3 and the second by 4:

-9p - 12c = -1320

16p + 12c = 1880

Adding the 2 equations:-

7p = 560

p = 80.

Substituting for p in first equation:

3(80) + 4c = 440

4c = 440 - 240 = 200

c = 50.