Question

A bag contains 2 coins. some of them are 10 cents coins and all of the others a 5 cent coins.

i) if the number of 10 cent coins is x, write down an expression for the number of 5 cent coins
ii) write down a expression, in terms of x, for the total value, in cents of the 24 coins

Answer 1

i) 24 - x

ii) 5x + 120

Explanation:

i) There are a total of 24 coins. We see that x of these 24 are 10 cent coins. The rest must be 5 cent coins, so they must be all the 24 coins that are NOT included in the x: 24 - x

ii) We know that there are x 10 cent coins, which are each 10 cents. There are also (24 - x) 5 cent coins, which are each 5 cents. In order to find their total value, we need to multiply the value of the denomination by how many there are of each denomination. So:

10x + 5(24 - x) = 10x + 120 - 5x = 5x + 120

Hope this helps!