Sam and Jack share out £80 in the ratio 5:3, in that order. How much do they each get?

First, you add the 5+3 to get 8. Now you know there are 8 'portions' of the £80 needed to be shared out. So £80/8 is 10. Sam needs 5 portions so 5x10=50 and Jack needs 3 portions so 3x£10 is £30.