Please help me I'm really confused on how you figure these out

Suppose there is a simple index of three stocks, stock abc, stock xyz, and stock qrs. stock abc opens on day 1 with 4000 shares at $3.15 per share. stock xyz opens on day 1 with 5000 shares at $4.30 per share. stock qrs opens on day 1 with 6000 shares at $4.60 per share. the price of stock abc on day 8 begins at $3.50. the price of stock xyz on day 8 begins at $3.90. stock qrs opens on day 8 with a price of $4.50 per share. assume that each stock has the same number of shares that it opened with on day 1. what is the rate of change of this simple index over 1 week?

Atriangular bandana has an area of 46 square inches. the height of the triangle is 5 3 4 inches. enter and solve an equation to find the length of the base of the triangle. use b to represent the length of the base.

True or false look at the picture pls : /