https://gyazo.com/540d819fa8a14cbccdbd2b43791a5a80
I really just need some guidance on part (a), because I don't really know how to turn that into a system.
If I had to guess I would solve for each variable but that would only give me 3 equations.
https://gyazo.com/540d819fa8a14cbccdbd2b43791a5a80
I really just need some guidance on part (a), because I don't really know how to turn that into a system.
If I had to guess I would solve for each variable but that would only give me 3 equations.
There are 4 unknowns (a,b,c,d) so you will need 4 equations if you want to solve them.
Look at Lake b: What lakes are upstream of it? What is the average of the salinity of these upstream lakes?
Look at Lake d: Do the same.
Look at Lake 30: Do the same.
This will give you three more equations - they've given you the other one.
Come back if you need help after you've tried that.