Answer:
The fraction of the people who choose curry = 
Step-by-step explanation:
As given,
Starter Main course
Soup Lasagna
Prawns Curry
The number of people who choose soup: the number of people who choose prawns = 2 : 3
Of those who chose soup,
The number of people who choose Lasagna : the number of people who chose curry = 5 : 3
Of those who chose prawns,
The number of people who chose Lasagna : the number of people who chose curry = 1 : 5
Let total number of people goes to restaurant = 5x
People who choose soup =
×5x = 2x
People who choose prawns =
×5x = 3x
Now, given,
Of those who choose soup,
The number of people who choose Lasagna : the number of people who chose curry = 5 : 3
So,
People who choose Lasagna after choosing soup =
×2x = 
People who choose Curry after choosing soup =
×2x = 
Also, given,
Of those who chose prawns,
The number of people who chose Lasagna : the number of people who chose curry = 1 : 5
So,
People who choose Lasagna after choosing prawns =
×3x = 
People who choose Curry after choosing prawns =
×3x = 
So,
Total number of people who choose curry =
+
= 
So ,
The fraction of the people who choose curry = 