Annie and her girlfriend, Estella, were talking about how heavy their backpacks were as they prepared for a hike. They decided to weigh them to see which was heavier. Annie’s backpack weighed 18.2 lb. and Estella’s weighed 16.75 lb.How much heavier was Annie’s backpack?

To find out how much heavier Annie's backpack is, we subtract Estella's backpack weight from Annie's backpack weight: 18.2 lb - 16.75 lb = <<18.2-16.75=1.45>>1.45 lb

Annie's backpack is 1.45 pounds heavier. Answer: \boxed{1.45}.

To find out how much heavier Annie's backpack was than Estella's, we need to subtract Estella's backpack weight from Annie's backpack weight.

Annie's backpack weight: 18.2 lb.
Estella's backpack weight: 16.75 lb.

So, to find the difference, we subtract Estella's weight from Annie's weight:

Annie's backpack weight - Estella's backpack weight = 18.2 lb - 16.75 lb

Now we can calculate the difference:

18.2 lb - 16.75 lb = 1.45 lb

Therefore, Annie's backpack is 1.45 lb heavier than Estella's backpack.