Two cubes and one pyramid weigh 9 lb. Seven cubes and two pyramids weigh 24 lb. All cubes weigh the same, and all pyramids weigh the same. What is the weight of one pyramid?

Answer: 5 lb

Explanation: Let x be the weight of a cube. Let y be the weight of a pyramid.

The first sentence becomes: 2x + y = 9.

The second sentence is: 7x + 2y = 24.

Solve this as a system of equations by any method you choose… substitution, elimination, Cramer’s Rule, etc. Or use my TI-84 Plus program ‘CRAMER’.

x = 2, y = 5

‘y’ is the weight of one pyramid, so the answer is 5.