Puzzle of the Week #43 - Hypothesis

You have in front of you five cards that are coloured on both sides. The five visible faces are red, blue, green, yellow and orange.

You are given a statement that:

‘If a card has red on one side it must have either blue or yellow on the other side’

You decide to turn over some of the cards in order to discover whether this statement is true or false. Which cards do you need to turn over?