I need help with my starr review again im littarly sorry.. its math!

Bed a is seven feet long. bed b is 7/8 of bed a. bed c is 7/8 of bed b. bed d is 7/8 of c. a. come up with an expression for the length of bed d. b. what is the length of bed d?

What is the equation of the graph below? y=sec(x)-4

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