A variable has the density curve whose equation is y = 1 for 0 < x <

Question:

A variable has the density curve whose equation is y = 1 for 0 < x < 1, and y = 0 otherwise.
a. Graph the density curve of this variable.
b. Show that the area under this density curve to the left of any number x between 0 and 1 equals x. What percentage of all possible observations of the variable
c. lie between 1/4 and 3/4?
d. exceed 7/8?