Matt and cat win £120 on the lottery and decide to share the winning ratio 1: 2

The way to work out how much each person gets is to find out how much one part is worth.

We can do this by adding the ratio (1:2) which gives us 3.

Divide £120 by 3 parts and you get £40 as one part. 

Because the ratio is one part : two parts, Matt gets £40 and Cat gets £80. 

Divide £120 by the ratio numbers added (3) and then multiply that number by 2 and put it in the correct place:
£120 / 3 = 40 x 2 = 80
40:80