Explanation:
since they are in order points p and q are in the middle and points O and R are on the end so they say that OR=36 since you don't know the exact lengths of all of the lengths in the middle from O to R then you multiply 5,6 and 1 by x and add
5x+6x+1x=12x
so then the whole length is equal to the ratio of 12x and also 36 so set those to equal each other
12x=36
x=3
so that is just the ratio and since they are asking for the length of O to Q that means that it is just 5x+6x=OQ
11x=OQ
insert x=3
33=OQ
Hope that helps :)