How do i write 7 23/40 as a decimal

You will get 25 points an image of a rectangular prism is shown below: part a: a cross section of the prism is cut with a plane parallel to the base. what is the name of the shape created by the cross section? explain your answer. (5 points) part b: if a cross section of the prism is cut perpendicular to the base, what would be the shape of the resulting cross section? explain your answer. (5 points)

Anyone know? is appreciated! will mark brainliest if correct!

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?