How many diagonals can be drawn from each vertex of a 16-gon?

What is the sum of these mixed numbers 2 1/8 + 4 3/8

Can someone check if i did this correct. it’s number 4 if you’re wondering.

The length of a rectangle is x times the square root of 100. the width is one-half y more than three-halves x. given that the area of the rectangle is 125 cm2, which equation could represent the rectangle in terms of x and y? a) 5xy − 15x = 125 b) 5xy + 15x = 125 c) 15x2 − 5xy = 125 d) 15x2 + 5xy = 125