Your math is right, but im not sure how to answer the question, sorry.
Answer:
46,206
Step-by-step explanation:
simple math
Black line m = -1/2 b = 2
blue line m = 1/3 b = -3
green line m = 2 b = 1/2
hope this helps.......
It is an inverse relationship.
There is enough food for 156*125=19500 person-days.
If the food can last (125+70)=195 days, there are
19500 person-days / (195 days)
= 100 persons