What is proportion and ratio?
A ratio is a way to compare two different things and is usually written as 1:2. A proportion is simply a statement that two ratios are equal.
To write a ratio, we need to be comparing the same type/s of a thing, preferably so it is the same unit of measure. Ratios can only be whole numbers and a ratio that is worked out as 2 : 1/2 would need to be doubled up to 4 : 1.
The video to the right explains how we would write the ratio if we needed to write down 1 part 2stroke oil to 10 parts petrol as a ratio. 

To simplify a ratio, factor out both numbers in the ratio and find the highest common factors that both numbers in the ratio share. Divide both numbers in the ratio by the highest common factor.
The video to the right shows my preferred way of simplifying small numbers in ratio and large numbers in ratio. 

How to work out this ratio:
Step 1: Add the ratio together. 2 + 3 = 5. Step 2: Divide £300 by 5. Step 3: You should get £60. Multiply this by how much Fred gets (x2). Step 4: Multiply £60 by how much Mark gets (x3). Step 5: Your answer is £180! The video to the right explains the step by step process. This is a grade 4 question so it is good to revise and make sure you're comfortable with before the exam! 

How to work out this ratio:
Step 1: Add the ratio together. 1 + 3 = 4. Step 2: Divide 20 by 4. Step 3: You should get 5. Multiply this by 1 litre (x1). Step 4. Multiply 5 by 3 litres (x3). Step 5: Your answer is 15 litres! This video the right explains the step by step process. This is a grade 4 question so it is good to revise and make sure you're comfortable with before the exam! 

How to work out this ratio:
Step 1: Identify the fraction. In this case, our fraction is 1 over 4. Step 2: Identify the parts of the fraction. We can see there are 4 parts, 1 part contains nuts and the other 3 parts do not contain nuts. Step 3: As ratio works in parts, we do not need to show the whole (like we would in a fraction), so we can just write it as 1 (part nuts) : 3 (parts no nuts). This video the right explains the step by step process. This question was worth 2 marks in the exam so it's a great one to practice to become comfortable with converting fractions to ratio. 

So we know there is no possible way of showing 3/5 : 1 as a ratio because ratio's have to be whole numbers.
Step 1: Multiply both sides by 5 (as that is the denominator). 3.5 x 5 = 3 and 1 x 5 = 5 so the answer is 3 : 5. Have a look at the video to the right where I have explained the steps. This may not appear in a Foundation GCSE paper, however, it is good to have an idea of how it works just in case it makes an appearance. 
