If I wanted to create a formula to show an additional increase to something, would I use exponential or linear form?

For example: A town produces enough food to feed 12 million people, and is increasing its food
supply to feed an additional 160,000 people per year.

How would I show that they've increased their current food supply to feed an additional 2 million people?

Question

If I wanted to create a formula to show an additional increase to something, would I use exponential or linear form? 

For example: A town produces enough food to feed 12 million people, and is increasing its food
supply to feed an additional 160,000 people per year.

How would I show that they've increased their current food supply to feed an additional 2 million people?

anonymous · Answer

add implies linear

anonymous · Answer

Thanks... So could I write my formula as:
y= b+mx
let b = 12000000+2,000,000
let m = 160000
let x = year

y= 14,000,000 +160,000x ?