The cost of 2 bottles of water and 4 apples is $5.50. The cost of 3 bottles of water and 5 apples is $7.50. Find the cost of one apple and the cost of one bottle of water using elimination. 

You could use a simultaneous equation to work this out. The price of an apple would be 75 cents. The price of a bottle of water would be $1.25.