Answer:

Step-by-step explanation:
Given



Required
Determine the number of adults
First, we need to calculate the number of children

Given that: 
Substitute 170 for Girls in 

Convert to fraction

Cross Multiply

Divide both sides by 2



So, the number of children are:



Next, we calculate the number of people in the cinema.

Substitute 765 for Children

Make People the subject.



If 3/5 are children, then 2/5 are adults.
So:




There is a 35% chance the first one will not work, and a 49% the second one will not work. (Theoretically there is an 81% chance neither of them will work.)
Not congruent is the answer