How do we multiply with mixed numbers using area models. 1/2 x 2 1/2

1. what is the formula for finding the vertical distance between two points on a coordinate plane?

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)

Julia bought 7 hats a week later half of all her hats were destroyed in a fire. there are now only 12 hats left with how many did she start