Three kilograms of jam and two kilograms of butter cost $29 and six kilograms of jam and three kilograms of butter cost $54. Find the cost of one kilogram of jam and one kilogram of butter.

Answer 1

3J + 2B = 29

6J + 3B = 54

multiplies the first equation by -2 and adds to the second equation:

-B = -4

B = 4

3J + 2(4) = 29

3J + 8 = 29

3J = 21

J = 7

Jam cost $7 per kilogram and the butter costs $4 per kilogram