1 and 3 are common factor
Do you have an iea of what do to before i give you the answer?
The 4th one because when you divide 270 by 15 you get 18 and when you also divide 135 by 7.5 you get 18 when something is proportional you get the same answer
1+2=3.
30/3=10
10x1=10
10x2=20
So the answer would be £10:£20
And to check if it’s right £10 + £20= £30