There are several information's of immense importance already given in the question. Based on those given information's the answer can be easily deduced. Let us now focus on the problem in hand.
Height at which the storeroom is located = 5 meters
Length of the ramp = 10 meters
Let us assume the angle = x
Then
Sin(x) = 5/10
= 1/2
Sin(x) = Sin(30)
x = 30 degree
From the above deduction, we can conclude that the ramp should have an angle of elevation of 30 degrees.
